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Old Dec 16, 2010, 12:45 PM   #11
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In Camera Raw, I got to see the actual PPI of my photos > 240 !
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Old Dec 16, 2010, 12:54 PM   #12
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In Camera Raw, I got to see the actual PPI of my photos > 240 !
No, PPI is not a meaningful concept apart from an actual physical print. What you see is boilerplate. Often, these things say 72; mine says 300; but there are no pixels per inch on something that doesn't have any inches -- how many inches across is the raw file? The very notion is meaningless.
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Old Dec 16, 2010, 12:55 PM   #13
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In Camera Raw, I got to see the actual PPI of my photos > 240 !

At the same time it is also 200, 150, 72, 50 etc.... PPI only has meaning when you consider the SIZE. PPI = # pixels divided by # inches. So, that value of 240 ASSUMES a certain number of inches. It is not 240 regardless of 4x6 or 8x10 or 16x20 print size.

Let's take a simple example - assume an image file has 3000 pixels in width by 2000 pixels in height.
if printing 4x6, you have 3000/6 = 500 dpi
if printing 8x10, you have 3000/10 = 300 dpi
if printing 11x14, you have 3000/14 = 214 dpi

See how dpi/ppi changes based on how you print? DPI is not a constant attribute of an image - the number of pixels is. You use that pixel count to calculate out dpi at the size you intend to print.

Now, in the above example if I take my 3000x2000 pixel image and heavily crop it I may only have 1000x500 pixels left. So suddenly if I want to print 8x10 I am only at 1000 / 10 = 100dpi which is poor quality.
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Old Dec 16, 2010, 4:39 PM   #14
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I finally got it...all because of you guys !

But something else came up: someone told me that colors where looking odly on paper because their photos were in Adobe RBG I think...he told me I should be careful, and check that my photos are in sRGB !

Well, when I look at the EXIF > Color Space: Uncalibrated...

So do I have to asign an ICC profile automatically ?

In CS4, everytime before opening a photo the program would ask if it should color manage it...since I installed CS5 2 days ago, I'm not getting that message anymore !

What's the difference between color space, color management, ICC etc ?

Where can I check the ICC profile of my pics, to make sure they're not in Adobe RGB ?

God, this is so complicated...
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Old Dec 16, 2010, 4:51 PM   #15
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now you've gone and done it! lemmee give you the simple answer. use sRGB until you have a reason not to.
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Old Dec 16, 2010, 5:07 PM   #16
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Why not convert sRGB to ProPhoto RGB ? Won't it look better on print ?

lol, what's with the worms ?
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Old Dec 16, 2010, 5:13 PM   #17
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can of worms!
http://www.wisegeek.com/what-does-it...n-of-worms.htm
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Old Dec 16, 2010, 6:09 PM   #18
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lol, you English-speaking people have such weird metaphors !

How about my last question ?
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Old Dec 16, 2010, 6:14 PM   #19
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i've stretched the limits of my knowledge too much already. and not been challenged either.

when i need a bit more in depth info, one of the places i go is
http://www.cambridgeincolour.com/tutorials.htm

maybe that'll help.
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Old Dec 16, 2010, 6:46 PM   #20
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Adobe RGB has more colors than sRGB. The problem is, many consumer printing companies don't allow for printing with the Adobe RGB color space. So the photo gets converted to sRGB. So if you set it up on your computer and process it with Adobe RGB, you may introduce colors that won't translate 1 for 1 to print so the print ends up looking differently. So to take advantage of Adobe you need a print process that will respect that profile set in the image. Think of it like making a photocopy of a color picture on a black and white copy machine - doesn't look as good as if you set the image up black and white in the first place.
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