** DPI and YOU ** -A POTN informational service-

[Crost_10D]

Hi guys. I was suprised a little when found out that 20d has 72dpi vs 10d 180dpi in image. Is true or may be it is changable. I do know how it works but still wanted to ask pros out there if it matters?

[CyberDyneSystems]

This setting "DPI" is meaningless in a digital image.

You can change it to whatever you want to in PS and no actual changes will be made to your images.
Feel free to set it to 3000DPI.. it will not change a thing ;)

[griff2]

CyberDyneSystems wrote: Feel free to set it to 3000DPI.. it will not change a thing.And then you can print your own postage stamps.;)

[CyberDyneSystems]

:rolleyes: .. O-kay.. well if you print using the DPI settings.. then it will effect the prints.. ;)
(But you'd rarely want to print @ 72 DPI either would you? )

So let me repharase.. changing DP settings on a Digital image will not effect the Digital Image.. it will ONLY effect the print out put IF you use the DPI setting to scale your prints.

Whatever the cameras defaults are make no difference as you would rarely if ever use the cameras defaults to actually make the prints.. you would specify the DPI to suit your own printing needs..

If you need postage stamps... then feel free to set it to 3000 DPI ;) :lol:

[Crost_10D]

I know all that guys... but why in the world 10d had 180 and 20d 72? oooo that's the question anybody hardly can answer right?

[Hellashot]

I know all that guys... but why in the world 10d had 180 and 20d 72? oooo that's the question anybody hardly can answer right?

It's the default setting for the image when opened. It'll give the "image size" as something huge - like 48x60". 72DPI is a standard DPI for web images. All that matters is now many pixels you have and what size you want to print at. A 6MP Drebel image at 300DPI (standard photographic quality) is 6.8"x10.2"

[pcasciola]

but why in the world 10d had 180 and 20d 72?Probably because back when the 10D was in production, everyone said, "Why is the 10D 180dpi while other cameras are.......", so for the newer models they decided to go with the more common default resolution of 72 dpi which is also the default dpi of most graphics programs, the standard web graphics resolution, and the old standard for computer monitors as well. Although today most monitors are 90-120 dpi or even higher on some smaller devices.

[Pekka]

http://www.scantips.com/no72dpi.html
Good reading for 72 dpi fans :)

[CyberDyneSystems]

:lol: lol: Oh.. that's good!

[CyberDyneSystems]

Probably because back when the 10D was in production, everyone said, "Why is the 10D 180dpi while other cameras are.......

:lol:
This is more thasn just funny..

Really .. the image almost has to contain some sort of DPI setting... I suppose it could be zero.... ???

But really.. what setting should it be?

No default will ever be correct except by some accidental miracle at printing time.. so no matter what number Canon chooses as default it will allways be wrong 99.99999999999999% of the time.

Mind you.. I'd rather print at 180 than 72 ;)

[elbirth]

ok, I've got a question since this has been brought up, it's confused me somewhat for a while....

I know DPI is only relevant for printing pictures, but what about PPI (Pixels Per Inch)? This is what the 20D defaults to for JPEGs it saves. In Photoshop, if you leave Resample checked and change the PPI, the pixel number changes (of course) but the document size in inches stays the same. However, if you turn of resampling, the document size in inches changes.

I don't understand this.... a while back I did a shoot for a campus group's CD cover they were doing... I gave them the JPEGs because they were having someone edit them. They called and said they were only 72 PPI and requested 300... so I just processed the RAW photos I took and gave it to them. I asked around and I was told that I could just change that in Photoshop without needing RAW, but doesn't that change the document size?

I'm confused.....

[AJSJones]

ok, I've got a question since this has been brought up, it's confused me somewhat for a while....

I know DPI is only relevant for printing pictures, but what about PPI (Pixels Per Inch)? This is what the 20D defaults to for JPEGs it saves. In Photoshop, if you leave Resample checked and change the PPI, the pixel number changes (of course) but the document size in inches stays the same. However, if you turn of resampling, the document size in inches changes.

I don't understand this.... a while back I did a shoot for a campus group's CD cover they were doing... I gave them the JPEGs because they were having someone edit them. They called and said they were only 72 PPI and requested 300... so I just processed the RAW photos I took and gave it to them. I asked around and I was told that I could just change that in Photoshop without needing RAW, but doesn't that change the document size?

I'm confused.....
The only correct way to refer to image resolution is PPI - pixels per inch, it's completely unambiguous. DPI was originally "dots per inch" and then became either that or "droplets per inch" referring to inkjet printers. So you can print a 300 PPI image on an inkjet printer at 360, 720, 1440 or 2880 dpi (as examples) and it'll be the same size, but with increasing quality - DPI should be restricted to describing printer dot/resolution capabilities.

The resample checkbox allows you (to decide if you want) to change either the document size or the file size depending on whether it's unchecked or checked, respectively. If, for example, you have a picture at 4x5 inches at 300 pixels per inch (1.8 megapixels) and you change the resolution to 72 pixels per inch, you either get a 16.66 x 20.8 inch image (unchecked so the image is still 1.8 MP) or a 4x5 inch image at 72 pixels per inch with just 0.1 megapixels (checked - you just lost most of the information in the image! Perhaps that's why they didn't like the 72 dpi images.)

[SkipD]

For all practical purposes, DPI and PPI are one and the same thing.

If you had edited a .jpg file in Photoshop and resaved it, you would have lost some of the original file's quality. A .jpg should be only the final product rather than an intermediate file type. I do all my editing in .TIF or .PSD formats, and when all is done I might save the results to a .jpg if there is a need to do so.

[Curtis N]

CyberDyne has said all that needs to be said, but if you don't believe him, here is an excellent article by Bob Atkins that helps explain DPI, PPI, etc.
http://www.photo.net/learn/resize/

[Jonny]

Ok,

So when you open a RAW file and save to Tiff in Adobe Camera Raw what settings do you use?
It gives you the option to set file size in pixels x pixels and DPI.
I normally use the 8 megapixel size (20D) at 300 dpi.

If i choose a larger pixel x pixel size does this resample the image to make it bigger?

[elbirth]

Ok,

So when you open a RAW file and save to Tiff in Adobe Camera Raw what settings do you use?
It gives you the option to set file size in pixels x pixels and DPI.
I normally use the 8 megapixel size (20D) at 300 dpi.

If i choose a larger pixel x pixel size does this resample the image to make it bigger?


yes, it does
generally, though, if you want to blow up a picture, doing so directly from the RAW image would probably be your best bet, since it's coming directly from the RAW data, instead of an already saved image. I do the same, though, at 8MP and 300DPI (which also gets carried over to being 300PPI).

[AJSJones]

" I do the same, though, at 8MP and 300DPI (which also gets carried over to being 300PPI)."

Jonny, elbirth, Photoshop's ACR does NOT let you do anything to set a DPI value. The size of the image is described as " number x number " and the tag is as "pixels per inch" You are seeing what you *want" to see. The Bob Atkins article Curtis linked to also makes the same point : DPI is only sensible to use when describing printer properties. The sooner this concept gets out, the fewer people will be confused by the misuse of DPI.

[elbirth]

" I do the same, though, at 8MP and 300DPI (which also gets carried over to being 300PPI)."

Jonny, elbirth, Photoshop's ACR does NOT let you do anything to set a DPI value. The size of the image is described as " number x number " and the tag is as "pixels per inch" You are seeing what you *want" to see. The Bob Atkins article Curtis linked to also makes the same point : DPI is only sensible to use when describing printer properties. The sooner this concept gets out, the fewer people will be confused by the misuse of DPI.


sorry, I should have clarified. I use CaptureOne to process my RAW files mostly, which DOES have a text box to enter DPI, which is why I said that carries over to PPI in Photoshop (whatever I set in CaptureOne's 'DPI' box shows up as PPI in Photoshop).
I understand the difference between the 2 (I do enough large-scale digital printing to where it gets embedded) but my question further up about my confusion was based around some people in the past having told me I could simply change things in Photoshop without altering the image... which I believe I have sorted out now

[AJSJones]

Then Capture one should go and stand in the corner and repeat after me......

[alan breslow]

If I give someone a cd of the 250 pics I shot for them... They take it to the store and get prints made at 72dpi... they will stink!

I may have made an error by getting this.

[robertwgross]

My camera produces files that are 72 or 200 or 1000 DPI. I don't really care. I shoot only RAW files. When the RAW files get to the RAW converter, I make my tweaks and adjustments, and then hit the "CONVERT" button to make them into TIF files. One of the settings in that converter is to make all of the TIF files at 300 DPI, which is kind of a foolproof standard. I suppose I can change it if I need.

One of the big online print companies wants files with 254 DPI. OK, I can set my converter to do that, or I can do it in the image editor program.

---Bob Gross---

[Curtis N]

One of the big online print companies wants files with 254 DPI.I have to wonder why they care. Or maybe they just want 254 DPI or higher for optimum quality, given the pixel count and the print size ordered?

If i'm ordering 4 x 6 prints, I would need to downsize the images to 1524 x 1016 pixels to get that DPI.

Care to share the name of that big online print company?

[robertwgross]

I have to wonder why they care. Or maybe they just want 254 DPI or higher for optimum quality, given the pixel count and the print size ordered?


It probably depends on the automated print machine that they use. It can probably handle other DPI settings, but it would have to buffer everything first, do some conversion, and that slows down their process. Most of those online companies have to concentrate on doing everything very fast. El-Co, maybe?

Some automated print companies don't care, and they will produce the print even into a totally wrong DPI print (e.g. a 4x6 inch print at 40 DPI).

---Bob Gross---

[kalmo]

Ok, there seems to be a REAL problem here regarding dpi, ppi, etc..
People just assume that dpi is an acronym for quality!
This scares me!
What if i told you that an image at 1dpi, yes 1dpi, is the same as one at 3000 dpi?!
You will surely call me a fool and throw rotten cabbages at me, but the only factor which affects quality is the actual pixel count of an image. You computer only works in pixels, so lets say you video settings are 1024x768, there will be 1024 pixels horizontally and 768 vertically, no matter if you have a 14inch monitor or a 21inch monster! When you are in photoshop, and you zoom to 100%, it means that you are viewing everypixel, in the sense, there will be,a bit less due to the actual PS window, but 1024 pixels across.
Now when it comes to printers, this REALLY scares me, coz people get SO caught up in the marketing hype. i hear ABSURD things such as 9000 dpi and so on......this is USELESS.
People just assume that each Dot, or droplet(D.P.I.-droplet/dot per inch) will represent a pixel, and how wrong this is. The printer will most likely print at 720 DPI or less, and then use say 10 dropletsor so to make up that pixel, so that the shade variations are nicer.
That print companies want 'HIGH RES' images has NOTHING to do with quality,now read that again...NOTHING to do with quality. AS mentioned by robertwgross, its to do with saving time, because you are giving them an image in pixels, and the PPI/DPI setting will get adjusted to meet the paper size. And if you do this for them, it saves a little time.and time is money! I hope this had made things a bit clearer, i know that i was so confused about it. The 'resolution' of your screen will depend on the video setting, and the size of your screen, changing an images dpi setting in photoshop will have NO difference on its size, the pixel number is STILL the same.
All the best, im off to put my flame suit on:D
K

[danavery]

Hi,

Can anyone tell me how to change a setting in the Canon 350D to save images at different dpi? I need to save images at 300 dpi (as opposed to 72 DPI) as an input for some custom post processing software. Not having to do this step in PS would be a time saver. I am aware dpi isn't really an issue ( until you print) but the post processing software Ihave uses it to resize images.

Thanks for your help on this issue.

[blue_max]

Don't forget that size is a factor too.

For example (just for clarity, not actual figures).

10cm square image at 72dpi, printed same size. File size 235k.
10cm square image at 144dpi, printed same size. File size 940k.

5cm square image at 72dpi, printed same size. File size 60k.
5cm square image at 144dpi, printed same size. File size 235k.

So if you wanted a print at 5cm at 144dpi and you had a file at 10cm, but 72dpi, you could print at 50% size and get your result.

If you have a large file and made it 72dpi, it would view very large on screen. To make it view at a reasonable size, you would have to make the file size very much smaller. Or, use a programme like photoshop, where you can view files at a reduced magnification.

If you have a large file at 72dpi, when reduced to print at smaller size, it would multiply the dpi value by the reduction.

Graham

[stov]

Ok, first post by me, and hopefully I will not get things messed up and be misleading. I agree with the whole computer side is all pixels based, you change your DPI setting in PS and you will see your pixel size shoot up and the document size remain the same. I have a 350D myself, and I did get a bit caught up in the whole 75DPI thats lousy, but look at the ducument size, its about 48 cm (I think) in its longest dimension, so here is what I do if I want to change the DPI for printing, select and copy the one of the pixel dimensions, alter the DPI, then paste back the pixel dimension, you will see that the document size shrinks, all depending on how large you make the DPI. Now for my turn to get my head on the chopping block, if you alter the DPI and leave the pixel information the same, surely PS is creating pixels now, this will make your image loose quality due to its manufacturing information that was previously not there, keep the pixel sizes the same if you alter the DPI would be my advice. Its the old rule of never if you can increase the size of a graphic image, as you will lose quality if you are using pixels (this does not apply for vectors, but as this is not a graphic forum I will stick with what the digitial photographs are using).
As for Danavery, the large setting on the 350D spits out a 75DPI image.. if you switch to RAW, this comes out as a 240 DPI image, with no need for rescaling your DPI through PS, another thing you can do in PS is set up some actions, so you record the action happening once, then you can apply the same action to other images with just a click of the mouse (might want to check out some Photoshop forum/tips (how to) site for the how to do that side if you need it more indepth).

Hope thats helped.. rather than clouded up issues and made me open for a good flaming :D

[Lani]

So what is the largest photo quality print can you get with an 8MP camera...either directly from and RAW file, TIFF or JPEG. Thanks :rolleyes:


yes, it does
generally, though, if you want to blow up a picture, doing so directly from the RAW image would probably be your best bet, since it's coming directly from the RAW data, instead of an already saved image. I do the same, though, at 8MP and 300DPI (which also gets carried over to being 300PPI).

[robertwgross]

So what is the largest photo quality print can you get with an 8MP camera...either directly from and RAW file, TIFF or JPEG. Thanks :rolleyes:

We can provide that size information as soon as you define what is "photo quality."

For small prints, 300 DPI is an excellent standard. As you start moving to the larger print sizes, the standards change. Maybe 150 DPI is all you can get. When you get to huge sizes, maybe 50 DPI is all you can get. The reason the standards slide is because of viewing distance. You don't view a 2x3 inch print at the same distance that you view a 2x3 foot print. As you move back to view the larger print, the DPI standard relaxes.

---Bob Gross---

[Lani]

Thank you Bob. Say I wanted to print a 11x14 or 16x20 photos that looks really really good, something I could frame and sell. I have an 8MP Rebel XT...what DPI would give me the best print quality...say I would be printing more 11x14s, what would you say the best DPI that would give me a quality print? I know 8x10 would be grand from what I have read, but what about 11x14? I have had labs print great looking 8x10s with my Fuji s5000 3MP camera! Thank you again :)


We can provide that size information as soon as you define what is "photo quality."

For small prints, 300 DPI is an excellent standard. As you start moving to the larger print sizes, the standards change. Maybe 150 DPI is all you can get. When you get to huge sizes, maybe 50 DPI is all you can get. The reason the standards slide is because of viewing distance. You don't view a 2x3 inch print at the same distance that you view a 2x3 foot print. As you move back to view the larger print, the DPI standard relaxes.

---Bob Gross---

[robertwgross]

Thank you Bob. Say I wanted to print a 11x14 or 16x20 photos that looks really really good, something I could frame and sell. I have an 8MP Rebel XT...what DPI would give me the best print quality...say I would be printing more 11x14s, what would you say the best DPI that would give me a quality print? I know 8x10 would be grand from what I have read, but what about 11x14? I have had labs print great looking 8x10s with my Fuji s5000 3MP camera! Thank you again :)

I guess you don't have a definition.

If you were trying to get to 300 DPI, the image straight from the camera will fall short for 11x14. For one thing, the crop aspect will be off. But, you will get most of 300 DPI at that size. Note that 300 DPI is a very high standard for that size, as I mentioned before. If you feel that you absolutely must get to 300 DPI, then you can first do interpolation (resampling). For some, that works. For others, it doesn't really buy you anything. Also note that for some printers, trying to boost the DPI up to a certain point is futile. The printer can't resolve it.

---Bob Gross---

---Bob Gross---

[Lani]

Gotya, thank you again Bob! :)


I guess you don't have a definition.

If you were trying to get to 300 DPI, the image straight from the camera will fall short for 11x14. For one thing, the crop aspect will be off. But, you will get most of 300 DPI at that size. Note that 300 DPI is a very high standard for that size, as I mentioned before. If you feel that you absolutely must get to 300 DPI, then you can first do interpolation (resampling). For some, that works. For others, it doesn't really buy you anything. Also note that for some printers, trying to boost the DPI up to a certain point is futile. The printer can't resolve it.

---Bob Gross---

---Bob Gross---

[tommypc]

Gentlemen. I create posters all the time from my digital and analog pictures. Here are some helpful tips. The majority of pictures that are to be printed are usually requested to be at 300 dpi. (Dots per Inch) However if you do a little homework you will find that most printers can't print above 200dpi, some even 150dpi. This includes some of the big poster printers. If you attempt to add information to a picture by resampling (upsampling) you are always going to see a decline in quality, you are adding false info to the picture. I have found there is no comparison between digital and analog pictures when it comes to printing, especially large format printing, analog wins every time. It is so much easier to scan an analog photograph to a high resolution thanit is to enlarge a digital photo. Pixels per Inch go out the window when you are talking printing. Dots per Inch are everything. Don't forget, most of the time if you are printing on a picture anything above 200dpi is usually a waste of storage space,the extra info of let's say a 1200 dpi picture is simply disguarded by the printer. Not to mention the extra time you will spend waiting for your printer to process the oversized file. The new cameras that put out 72dpi as a standard really erks me as they assunmed that most pictures will just be used on the internet or viewed on a computer screen or tv. Instead it would be nice if they would assume that you are going to want to make posters out of you photos and by default, the cameras should be capable of high resolution photos that can later be lowered if needed, which is the best way to do any picture. Taking away info to achieve a lower pixel count for web display is easy. To have to add info to a picture to falsely raise the pixel count is a bad idea. Have fun.

[Franko515]

Kinda confused here :oops: I have a S3 IS and it seems all my shots are at 180dpi, if I wanted to print 5x7 or 8x10 what would these need to be set to (send in pics to costco, or walgreens). Also as far as cropping what would the crop size need to be? Could I just crop to my liking, or does it have to be a certain crop size to get the prints I want?

Thanks in advance

[Franko515]

I just noticed how old this thread is :oops: Hope someone can still answer though :D

[tim]

Kinda confused here :oops: I have a S3 IS and it seems all my shots are at 180dpi, if I wanted to print 5x7 or 8x10 what would these need to be set to (send in pics to costco, or walgreens). Also as far as cropping what would the crop size need to be? Could I just crop to my liking, or does it have to be a certain crop size to get the prints I want?

Thanks in advance

Go read the thread again. ppi is irrelevant for most situations.

[EOS_JD]

Kinda confused here :oops: I have a S3 IS and it seems all my shots are at 180dpi, if I wanted to print 5x7 or 8x10 what would these need to be set to (send in pics to costco, or walgreens). Also as far as cropping what would the crop size need to be? Could I just crop to my liking, or does it have to be a certain crop size to get the prints I want?

Thanks in advance

180ppi means nothing. How many pixels do you have?

[Franko515]

Go read the thread again. ppi is irrelevant for most situations.


I have read the thread, and many others. There seems to be a difference of opinion (examples below) thus my confusion :oops:


Gentlemen. I create posters all the time from my digital and analog pictures. Here are some helpful tips. The majority of pictures that are to be printed are usually requested to be at 300 dpi. (Dots per Inch) However if you do a little homework you will find that most printers can't print above 200dpi, some even 150dpi. This includes some of the big poster printers. If you attempt to add information to a picture by resampling (upsampling) you are always going to see a decline in quality, you are adding false info to the picture. I have found there is no comparison between digital and analog pictures when it comes to printing, especially large format printing, analog wins every time. It is so much easier to scan an analog photograph to a high resolution thanit is to enlarge a digital photo. Pixels per Inch go out the window when you are talking printing. Dots per Inch are everything. Don't forget, most of the time if you are printing on a picture anything above 200dpi is usually a waste of storage space,the extra info of let's say a 1200 dpi picture is simply disguarded by the printer. Not to mention the extra time you will spend waiting for your printer to process the oversized file. The new cameras that put out 72dpi as a standard really erks me as they assunmed that most pictures will just be used on the internet or viewed on a computer screen or tv. Instead it would be nice if they would assume that you are going to want to make posters out of you photos and by default, the cameras should be capable of high resolution photos that can later be lowered if needed, which is the best way to do any picture. Taking away info to achieve a lower pixel count for web display is easy. To have to add info to a picture to falsely raise the pixel count is a bad idea. Have fun.


Ok, first post by me, and hopefully I will not get things messed up and be misleading. I agree with the whole computer side is all pixels based, you change your DPI setting in PS and you will see your pixel size shoot up and the document size remain the same. I have a 350D myself, and I did get a bit caught up in the whole 75DPI thats lousy, but look at the ducument size, its about 48 cm (I think) in its longest dimension, so here is what I do if I want to change the DPI for printing, select and copy the one of the pixel dimensions, alter the DPI, then paste back the pixel dimension, you will see that the document size shrinks, all depending on how large you make the DPI. Now for my turn to get my head on the chopping block, if you alter the DPI and leave the pixel information the same, surely PS is creating pixels now, this will make your image loose quality due to its manufacturing information that was previously not there, keep the pixel sizes the same if you alter the DPI would be my advice. Its the old rule of never if you can increase the size of a graphic image, as you will lose quality if you are using pixels (this does not apply for vectors, but as this is not a graphic forum I will stick with what the digitial photographs are using).
As for Danavery, the large setting on the 350D spits out a 75DPI image.. if you switch to RAW, this comes out as a 240 DPI image, with no need for rescaling your DPI through PS, another thing you can do in PS is set up some actions, so you record the action happening once, then you can apply the same action to other images with just a click of the mouse (might want to check out some Photoshop forum/tips (how to) site for the how to do that side if you need it more indepth).

Hope thats helped.. rather than clouded up issues and made me open for a good flaming :grin:



180ppi means nothing. How many pixels do you have?

Pixel Dimension X: 2629 Y: 2087 is this what you mean by how many pixels or do you mean the camera itself (sorry if this sounds crazy but this is all foreign to me) If you do mean camera it is a 6mp.

As for the cropping part of my question. Can I just crop to my liking and print say a 5x7, or does the image need to be a certain size (i.e. 800x600)

Also Tim, did you mean dpi? or is it true ppi and dpi area the same?

Thanks in advance

[tim]

You can ignore dpi. You can also ignore ppi. What matters is how many pixels you have. ppi is only required when you use some pro labs who insist you set up your files exactly as you want them printed. You can send an 1800x1200 file at 10ppi (ie 180 inches wide) to most print labs and say "print it as 6x4", it'll come back looking perfect, as they ignore the 10ppi.

If you want to print 5x7 you need a 5:7 ratio in the number of pixels in your image, else it'll be cropped. If you labs wants 300ppi that means you need 1500 x 2100 pixels in your image. You can set the ppi to 300 if you like, but like I said most labs won't look at this figure.

Hope that helps.

[Franko515]

You can ignore dpi. You can also ignore ppi. What matters is how many pixels you have. ppi is only required when you use some pro labs who insist you set up your files exactly as you want them printed. You can send an 1800x1200 file at 10ppi (ie 180 inches wide) to most print labs and say "print it as 6x4", it'll come back looking perfect, as they ignore the 10ppi.

If you want to print 5x7 you need a 5:7 ratio in the number of pixels in your image, else it'll be cropped. If you labs wants 300ppi that means you need 1500 x 2100 pixels in your image. You can set the ppi to 300 if you like, but like I said most labs won't look at this figure.

Hope that helps.

Thanks ;) so in review, I will forget about dpi and ppi and only worry about the crop (for a 5x7 the pixel dimension which I have listed needs to be divisable by 5 and 7, i.e. 2500 x 2100) In the event I need to change the dpi (if requested by printer) these number needs to be multiplied by 3 (if i wanted 300dpi) to get 1500 x 2100.

One more thing :oops: I crop my pic to taste, so after that should I put it in a program to change the pixel dimension. If so, what program could I use to convert them as a batch to say 5 x 7?

do I have this at least half right? Again sorry if these questions seem crazy, but this is all very new to me and I would like to have a clear understanding so I can help others if need be.

Thanks for all your help ;)

[amonline]

I get a kick out of these tech threads where no one knows what they are talking about... even funnier are the ones with suggestions and advice on things they don't know what they are talking about. :lol:

[Franko515]

I get a kick out of these tech threads where no one knows what they are talking about... even funnier are the ones with suggestions and advice on things they don't know what they are talking about. :lol:

If you know the correct info sir would you plz share, as I am looking for clarification on this issue.

Thanks in advance for any help you may provide
Franko

[amonline]

It's wayyy to late and wayyy to long to go into tonight... I'll check in again soon... sorry. I'm just tired of seeing 'photographers' trying to talk like graphic artists... and most of these are am-photogs. They really should keep out of these discussions. Yea, I'm being an ass... :oops:

[Franko515]

It's wayyy to late and wayyy to long to go into tonight... I'll check in again soon... sorry. I'm just tired of seeing 'photographers' trying to talk like graphic artists... and most of these are am-photogs. They really should keep out of these discussions. Yea, I'm being an ass... :oops:

Not a problem, however you need to get your point across sir ;) I look forward to your post.

Again thanks for any help you may provide
Franko

[amonline]

I threw this together real fast; but it's the ins and outs of resolution, photography, dpp and photoshop in layman's terms. There is deeper information on the subject, but I wanted to keep this tackle simple.

Resolution for Dummies (http://www.alanmillerphotography.com/documents/resolution_for_dummies.pdf)

Hope it helps...

[Franko515]

I threw this together real fast; but it's the ins and outs of resolution, photography, dpp and photoshop in layman's terms. There is deeper information on the subject, but I wanted to keep this tackle simple.

Resolution for Dummies (http://www.alanmillerphotography.com/documents/resolution_for_dummies.pdf)

Hope it helps...

Thank you sir :D Oh thank you so much, I actually understood the whole document :D Again thankyou sir ;)

[amonline]

Thank you sir :D Oh thank you so much, I actually understood the whole document :D Again thankyou sir ;)
You are most welcome. My goal was to keep things as simple as possible. There are too many people on this board trying to act like something they are not. I get sick of it at times. Simplicity is key. ;)

[tim]

Thanks ;) so in review, I will forget about dpi and ppi and only worry about the crop (for a 5x7 the pixel dimension which I have listed needs to be divisable by 5 and 7, i.e. 2500 x 2100) In the event I need to change the dpi (if requested by printer) these number needs to be multiplied by 3 (if i wanted 300dpi) to get 1500 x 2100.

One more thing :oops: I crop my pic to taste, so after that should I put it in a program to change the pixel dimension. If so, what program could I use to convert them as a batch to say 5 x 7?

do I have this at least half right? Again sorry if these questions seem crazy, but this is all very new to me and I would like to have a clear understanding so I can help others if need be.

Thanks for all your help ;)

Well you have to pay attention to the nubber of pixels, it's just the ppi figure you usually don't have to worry about. try and print a 25 x 35 pixel image 6x4 and it won't look so hot! dpi you can forget entirely.

You can't really batch convert to 5x7 as you lose part of your image, you have to choose which bit gets lost.

This may have been answered already i'm too tired to read the linked thread. Hopefully this makes sense.

[Franko515]

Well you have to pay attention to the nubber of pixels, it's just the ppi figure you usually don't have to worry about. try and print a 25 x 35 pixel image 6x4 and it won't look so hot! dpi you can forget entirely.

You can't really batch convert to 5x7 as you lose part of your image, you have to choose which bit gets lost.

This may have been answered already i'm too tired to read the linked thread. Hopefully this makes sense.

Thanks for taking the time to answer my questions sir ;) This is a great place to learn :D

[tim]

Thanks for taking the time to answer my questions sir ;) This is a great place to learn :D

No problem, people here taught me a lot so I help others. Hope it helps :)

[EOS_JD]

This is one of the most confusing posts I've read with so many people who actually believe they are right and are way off the mark! Fortunately Tim is there to rescue all who stray :-)

Here's a good links and my own explanation.

http://www.fotofinish.com/resources/centers/photo/resolution.htm

Here's how I see things.

What is important in all stages of image editing is the number and quality of the pixels you have.

Changing the size or resolution of an image with the resample box checked means you will be adding/subtracting information to/from the image. This will reduce the quality of that image as it's the software that is adding or subtracting the pixels and ultimately controlling the detail - although in most cases it does a pretty good job and you won't really see much difference unless you are trying to add/subtract a proportionately large number of pixels to an image - this can be true even with a high quality image.

If you have the check box empty however, you can change the print size of the image to any size you like but the number of total pixels will not change (the resolution will vary as you increase/decrease the print size). This can be important to retain maximum quality from your prints. You are keeping the same pixels but condensing them into a smaller area so the ppi has to increase...(same pixels, smaller area=more pixels per inch). Where by resampling in PS is adding/subtracting pixels to the over all image.

It's really a very simple relationship between the number of pixels(px) - print size (ps) (I'm assuming measurements are in inches) and the resolution (ppi).

px = ps x ppi

So it goes that

ppi = ps/px
&
ps = px/ppi

My 20D produces an image of 3504 x 2336 pixels. To retain the maximum detail I want to keep these pixels intact. I don't want photoshop adding new ones and I don't want it to be throwing away any either until I want to resize for the web or perhaps need to when printing.

When resizing for the web, generally I don't actually look at the actual size or resolution of the image. I want an image with a fixed number of pixels. Usually a maximum of 600 - 800 pixels on the longest axis. This gives a reasonable sized image on most screen resolutions.

Anyway I just enter a fixed number of pixels (say 600) on the longest axis - the other will change proportionately. This will give a pretty small image size but view at 100% and that's what you'll see on the web. You can use "save as" to save a jpeg or use "save for web" to get more control of the actual compression and size (in bytes).

Regards print size
When viewing your printed images you usually look pretty closely at a 6x4 or 7x5 print. You may view 10x8s slightly further away and you'll look at A3+ images say 19"x13" even further back. The maximum resolution a 20D image can print a 16x12 image is around 194 pixels per inch. I actually find anything above 180ppi this is fine for normal viewing distances of larger prints. Try it - Print one resampled to 300ppi and print one without resampling at around the 180ppi mark (no need to be too accurate with the ppi - just don't resample any print up to 19"x13". I regularly print larger images at 180ppi and don't see any difference.

I hope all this makes sense? Please ask if you have any further questions. I might nit be too great at explaining and if so let me know.

JD