DPI

[alpine62uk]

I wonder if someone can guide me through this subject.

I have a 1d MK11 and take most my photo in raw format. However I have just noticed that when I am working on them in photo shop the DPI is always 240 under the details in Image size.

I am correct in saying that I need a minimum of 300 for good prints and if so how do I go about getting the maxium DPI from the raw shots I have taken, is this a camera setting or Photoshop one that needs changing.

As you can see I am at a loss on this, so any help we be very welcome

[PacAce]

If you use ACR to do your conversion, set the the resolution to 300 DPI there (see the data at the bottom of the screen under the image?). If not, then set it in the conversion program you are using.

[lostdoggy]

The DPI optio is available during conversion from RAW to whatever. PS is note by PAC. DPP is after you click Batch radio button under output setting. Phase One C1 is under the process tab resolution.

[alpine62uk]

If you use ACR to do your conversion, set the the resolution to 300 DPI there (see the data at the bottom of the screen under the image?). If not, then set it in the conversion program you are using.

Ok Thanks for the reply, do you suggets I go higher than 300dpi? if so what are the guidelines

Thanks

Antony

[BigRed450]

I always use 300 DPI for printing. Any more then that won't do anything for you.
The DPI makes no difference what so ever while you are processing the images, pay no attention to it.
So don't worry about the DPI until you print, then when you resize the image for print you can specify the DPI while in the resizing dialogue.

[alpine62uk]

I always use 300 DPI for printing. Any more then that won't do anything for you.
The DPI makes no difference what so ever while you are processing the images, pay no attention to it.
So don't worry about the DPI until you print, then when you resize the image for print you can specify the DPI while in the resizing dialogue.

Thanks, but can you explain a little more. Are you saying that at the convert from Raw stage in PS that it is not relevant weather 240 or 300 DPI is selected, in other words the detail is there I just need to ensure 300 DPI is selected at the print stage?

Thanks

[etaf]

most covered above
PPI pixels per inch
theres little point in going above 300 - 300 is used for high quality, magazine, books, images which will be viewed closely.
240PPI i think is the preferred PPI for epson printers - you may not see a lot of difference between the two on your printer.
If the image is going to be put on a wall and viewed from a distance you can often get away with less PPI

so as said ignore PPI when working on the screen - all ppi does it determine the print size and that therefore depends on how many pixels in you image

if you take the pixels height and width and divide by the PPI you get how many inches will be possible to print that image at

try playing with different settings - you will see no difference

set to 72PPI

look in photoshop and it will still have the same pixels - but under image size you will see the print size is huge - but of course with only 72 pixels per inch on a print it will look awful.
just change the 72 to 300 in photoshop with resample off
the pixels stay the same bt the print size chages

[alpine62uk]

most covered above
PPI pixels per inch
theres little point in going above 300 - 300 is used for high quality, magazine, books, images which will be viewed closely.
240PPI i think is the preferred PPI for epson printers - you may not see a lot of difference between the two on your printer.
If the image is going to be put on a wall and viewed from a distance you can often get away with less PPI

so as said ignore PPI when working on the screen - all ppi does it determine the print size and that therefore depends on how many pixels in you image

if you take the pixels height and width and divide by the PPI you get how many inches will be possible to print that image at

Thanks, at last I think I have got it, sorry for being so dumb on this but I could not get my head around it.

Thanks

[etaf]

edit my last entry
this may help further
http://www.scantips.com/
or not

[BigRed450]

You got it. Only worry about DPI/PPI when printing....

[PacAce]

You got it. Only worry about DPI/PPI when printing....
BigRed is right about the DPI being almost irrelevant in the post processing (I say almost because when you're working with fonts, dpi is very relevant). However, most of the time, you'll want the DPI to be set at 300 anyway so why not just set it in ACR and then forget about it instead of having it set to 240 and then later on changing it to 300 every time you want to do a print?

[Mernya]

If you are working in photoshop with fonts, they change to reflect the current DPI unless you rasterize them. Vector fonts rock.

[blue_max]

Just to add a little to the mix as you all seem to be getting the hang of dpi.

300dpi is fine for regular four-colour print. This is typically samples at 150lpi (lines per inch). This determines the size of the printed dot.

These days it is possible to print at 175lpi and even 200lpi. This would be for high quality print such as calendars and annual reports where quality was paramount. The settings for these would be twice the lpi, so 350dpi and 400dpi respectively.

This assumes the picture to be used at 100% or same size. If it is being used at 50% then you can half the dpi and conversely, twice the size would require double the dpi.

Knowing the final useage is the only way of accurately supplying optimum image size.

This is important in print, because too little data will produce a poor result and too large will be difficult to manage and not be any better quality.

Graham

[PacAce]

If you are working in photoshop with fonts, they change to reflect the current DPI unless you rasterize them. Vector fonts rock.
Try working with fonts and making an action out of them and see what happens when the DPI of the image you used to create the action doesn't match the DPI of the image you are using the action on.

[RAitch]

Huh? DPI won't matter if you're just taking the image to get printed somewhere.
If you have a 72DPI image and a 600DPI image, if you print them both to the same size, there won't be any difference.

If your image is 3000 pixels by 2000 pixels (for simplicity sake) and you print the image out to a 3x2 image... how many dots per inch do you think the print will be?

It's dots per inch people. The resolution and print size will determine what the DPI are.
If you have an image that's 3000DPI, chance are it'll only print out in that resolution to a print smaller than a postage stamp. If you print to an 8x10, the DPI won't me 3000.... it'll have to adjust the DPI to get the print size that you want.

[blue_max]

Huh? DPI won't matter if you're just taking the image to get printed somewhere.
If you have a 72DPI image and a 600DPI image, if you print them both to the same size, there won't be any difference.

If your image is 3000 pixels by 2000 pixels (for simplicity sake) and you print the image out to a 3x2 image... how many dots per inch do you think the print will be?

It's dots per inch people. The resolution and print size will determine what the DPI are.
If you have an image that's 3000DPI, chance are it'll only print out in that resolution to a print smaller than a postage stamp. If you print to an 8x10, the DPI won't me 3000.... it'll have to adjust the DPI to get the print size that you want.

If you are intending to put this through a traditional print process ie not photographic, then the dpi is relevant. If the 72dpi and 600dpi are in fact the same size, then there will be a huge difference – and a different in file size. If the 72dpi image is much larger than the 600dpi image then indeed there will be no difference. dpi and size are very much linked.

Being as dpi is only relevant in traditional print, I am not sure what you are getting at here.

Graham

[etaf]

should really be PPI rather than DPI

Dots per inch are for printers and if you are printing one pixel can be represented by various dots of CMYK
http://www.ltlimagery.com/resolution.html
http://www.blaha.net/Main%20Picture%20Resolution.htm
http://www.scantips.com/basics03.html

[RAitch]

Maybe I didn't explain it right.
If you have an image and load in PS (72DPI) and save that as file 1... the do an image adjustment to make that image 600DPI and save it as file 2.... when you print the files (straight up) you'll get a big image (file 1) and a very small image (file 2). Since the printer is packing more dots per inch in file 2, it won't be as big.

If you then take those 2 files and send them to be printed in 8x10... they'll look the same (regardless of the DPI setting).

You can really screw with the image in PS by turning off resampling when changing the DPI... but that's for another thread.

[RAitch]

Of course if you have an image that's 3000px by 2000px and 72DPI (file 3) and and image that's 3000px by 2000px and 600DPI (file 4)... the larger file (file 4) will produce WAY BETTER results.

However, since we're all using cameras with a certain resolution restriction... without spending extreme $$, we won't be able to get images that have that much more data.

That would be like taking a sub MP camera from years ago and comparing it to the 5MP+ cameras of today. You could print an image from both cameras to the same size, but you'll get more DPI out of the higher resolution image (thus making it look better). That's also (obviously) why we can create larger images with the same clarity as older sub-standard cameras in a smaller print.

[etaf]

RAitch - that depends on how many pixels in the image
3000 x 2100
so print size at 300PPI
= 3000/300 > 10"
= 2100/300 > 7"

If set to 100PPI
then 30" x 21"

so changing the number of pixels to size 300 x210
at 300PPI print size is 1" x .7"
if you change this and sample up to 8" x10" it will look awful

so I'm not sure of your explanation


EDIT: you posted as i was composing - so OK

[blue_max]

Maybe I didn't explain it right.
If you have an image and load in PS (72DPI) and save that as file 1... the do an image adjustment to make that image 600DPI and save it as file 2.... when you print the files (straight up) you'll get a big image (file 1) and a very small image (file 2). Since the printer is packing more dots per inch in file 2, it won't be as big.

If you then take those 2 files and send them to be printed in 8x10... they'll look the same (regardless of the DPI setting).

You can really screw with the image in PS by turning off resampling when changing the DPI... but that's for another thread.

This has got very complicated! But essentially, I am latching on to the fact that dpi is being discussed and that is very relevant in my profession (graphic design/print).
When I mention large and small file, I refer to the megabyte size, rather than the screen size. In this context, size and dpi are extremely relevant. I think you describe that as resampling.

If anyone reading this, is intending to send to a photographic lab, then they do not need to be concerned with dpi.

Graham

[PacAce]

...You can really screw with the image in PS by turning off resampling when changing the DPI... but that's for another thread.
Actually, it's the other way around. What you don't want to do when changing DPI is to turn on resampling. You want that OFF, unless your intent is not just to change the DPI but to resize the image as well.

[blue_max]

To try and sum this thread up...

dpi matter only in traditional print. If you intend it to go to print, leave the file size as large as possible.

If you change the dpi and allow the file size to remain the same, there is no effect. When you import the picture into a page layout programme (Quark, Indesign etc) it will only alter the preview.

If you send your photos to a photographic lab, then you don't need to concern yourself with dpi.

If anyone wants more info on dpi – then please ask a specific question and I will answer it as concisely as I can.

Graham

[Mernya]

Summing up a DPI thread in 4 phrases? Ha! Let me try a whack at it. More than that in phrases, but less in concepts.

I think another thing to get people understanding is this:
1. Pixels are dots. Your computer screen shows so many depending on screen. 50 pixels is 50 pixels. When working on screen, you are working with dots and can zoom to see more or less at a time. At 100% zoom, you see as many dots as your current screen configuration. Your camera works in pixels, too.
2. Printers need a ratio of dots (or lines) or pixels per inch to know what to print. If you have a 300 pixel square image and print it at 300dpi, it will be one inch wide. If you print it at 150 dpi, it will be 2 inches wide, but will be a little softer/blurrier/pixelated. This is why you use the higher megapixels cameras when you need to crop areas or blow up images. It is why digital zoom is effectively worthless. A 2 inch image at 300 dpi has the same amount of pixels as a 1inch image at 600 dpi.; the file sizes are the same.
3. Printer resolutions are not standard. A 300 dpi continuous tone printer (where each dot would be a specific shade of color) such as a dye sublimation printer will look better than a 1200 dpi 4 color inkjet printer. A 1200 dpi 6/8 color inkjet printer will look better than an equivalent 4 color printer. Throw in printhead technology and other crud for more confusion.

[blue_max]

Summing up a DPI thread in 4 phrases? Ha! Let me try a whack at it. More than that in phrases, but less in concepts.

I think another thing to get people understanding is this:
1. Pixels are dots. Your computer screen shows so many depending on screen. 50 pixels is 50 pixels. When working on screen, you are working with dots and can zoom to see more or less at a time. At 100% zoom, you see as many dots as your current screen configuration. Your camera works in pixels, too.
2. Printers need a ratio of dots (or lines) or pixels per inch to know what to print. If you have a 300 pixel square image and print it at 300dpi, it will be one inch wide. If you print it at 150 dpi, it will be 2 inches wide, but will be a little softer/blurrier/pixelated. This is why you use the higher megapixels cameras when you need to crop areas or blow up images. It is why digital zoom is effectively worthless. A 2 inch image at 300 dpi has the same amount of pixels as a 1inch image at 600 dpi.; the file sizes are the same.
3. Printer resolutions are not standard. A 300 dpi continuous tone printer (where each dot would be a specific shade of color) such as a dye sublimation printer will look better than a 1200 dpi 4 color inkjet printer. A 1200 dpi 6/8 color inkjet printer will look better than an equivalent 4 color printer. Throw in printhead technology and other crud for more confusion.

It was kinda three points ;)

I felt this thread had got a little esoteric and left peole lost. Each answer seems to add fuel to the fire. Every answer I read, leaves me more confused and I know my area of expertise! Maybe the question is too general.

If we leave a few posters being pedantic, it will have served no purpose.

Can we agree that most people need not concern themselves about dpi unless the are going to traditional print?

If anyone wants to explore further, then come back with a specific question.

Graham

[Mernya]

Can I agree? Sure. :)
But the industry sure doesn't make it easy on people.

[RAitch]

Actually, it's the other way around. What you don't want to do when changing DPI is to turn on resampling. You want that OFF, unless your intent is not just to change the DPI but to resize the image as well.

That's what I meant... you can screw (in a good way) by turning resampling off when changing the DPI setting.

I'll shut up now. Bottom line... DPI doesn't matter for pretty much everybody... unless you're doing something other than bringing your files to a camera shop to get printed in standard sizes.

[Poco]

That's what I meant... you can screw (in a good way) by turning resampling off when changing the DPI setting.

I'll shut up now. Bottom line... DPI doesn't matter for pretty much everybody... unless you're doing something other than bringing your files to a camera shop to get printed in standard sizes.

Agreed, and even if you are printing them yourself the DPI in the file doesn't matter much. Most consumer programs allow you to specify the size of your printed output (4x6,5x7,8x10,etc.). They will not look at the DPI you set in the file. Even if they did care, you would still have to manipulate the DPI at the time of printing to get the right size (If you have a 3000x2000 image that you want at 6"x4" and 7"x5" you would have to set the DPI differently each time) so, getting back to the original question, there is no point in always changing it to some fixed size during a normal work flow.

One line conclusion - If you do not know exactly why you need to set the DPI then you don't need to.