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

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).

" 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

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

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.

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---

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?

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---

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
K

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.

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

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

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

Lani wrote:
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

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---

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