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Author Topic: Question about workspace profile  (Read 1406 times)

jack777

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Question about workspace profile
« on: August 08, 2011, 07:02:17 am »

Let's assume we want to print out a file which has no profile attached to it. When we open it we have a choice to either assign a profile to it or leave it without color management. The obvious choice when we want to edit the file is to assign ProPhoto/Adobe/sRGB. However if the only thing we want to do is print the file does it really matter? Does assigning a profile alters colors on the print?
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eliedinur

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Re: Question about workspace profile
« Reply #1 on: August 08, 2011, 07:52:24 am »

Quote
Does assigning a profile alters colors on the print?
First, it definitely changes the colors in the digital image because assigning changes the profile without changing the image data (numbers). A particular number represents a color only within the framework of a space and that color is determined by the gamut of the space. 200/40/40 is a different shade of red in sRGB, Adobe RGB or ProPhoto RGB. When you print, the color management finds the equivalent number in the printer's space which will reproduce the same colors it is given, which it knows by reference to the embedded profile. (Or, if those colors are out-of-gamut for the printer, the closest in-gamut substitutes.) What the printer prints depends on what it is sent. Send it different colors, because the profiles are different even though the numbers are the same, and it will print different colors.
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digitaldog

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Re: Question about workspace profile
« Reply #2 on: August 08, 2011, 10:37:50 am »

In all ICC conversions, there has to be two profiles (color spaces) defined. A source and a destination. An untagged document is always assumed to be in some color space even if that assumption is dead wrong. In Photoshop, whatever color space you have selected in the working space popup menus (Color Settings) is the assumption. So if you print an untagged document, Photoshop assumes this is the color space (that’s what the preview is based upon too). So yes, you must either assign the correct profile for the conversion to the print space OR a color space assumption will be made for you. IOW, it does make a difference when you print because two profiles are always necessary.
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milt

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Re: Question about workspace profile
« Reply #3 on: August 08, 2011, 01:03:02 pm »

One easy way to think about it is that the profile tells the world what the pixel color numbers in the file mean.   Unless the printer driver knows that 200/40/40 means such and such a red, it can't be printed (short of just making a guess).  Giving a different meaning to the pixel color numbers in a file of course changes how a printer will print them.

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Schewe

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Re: Question about workspace profile
« Reply #4 on: August 08, 2011, 01:07:16 pm »

Let's assume we want to print out a file which has no profile attached to it.

Why do you have an image with no profile? The general assumption would be it was an sRGB image that was saved for the web or that it was a CMYK image that was produced without the profile to make sure the printer didn't change the image. If not these two then I would suggest finding out why there was no profile and tell the person that didn't embed the profile that they need to in the future...to avoid problems and questions.
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jack777

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Re: Question about workspace profile
« Reply #5 on: August 10, 2011, 09:08:35 am »

Thanks, that's the answer I was looking for. I didn't fully understand why the colors change with different profiles while their numbers stay the same. And why I have to deal with such files? Well people bring files to print with all sort of different profiles (or no at all).
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