Assigning a Profile vs Converting a Profile

[robyn_geering1]

Hi there, can anyone explain to me in simple terms (if that is

possible), when you would assign a profile in Photoshop, as opposed

to converting to a profile. Many thanks

[peterblaise]

Assigning a Profile vs Converting a Profile

 

.

 

Hi Robyn,

 

In my understanding, "profiles" merely describe how a particular device handles colors, converting "raw" color numbers into specific colors that device is capable of handling.

 

In other words, "blue" in my mind might be coded in Red/Green/Blue numbers as 0,0,255, ... BUT that output may look like a completely different "blue" on my screen versus the qualities of the ink and paper in one of my printers versus the qualities of the ink and paper in another of my printers.

 

A "profile" (for EACH - for each device AND for each image file) will translate that 0,0,255 code into a native internal reference, different for each device, so the "blue" in my mind and on my calibrated and profiled screen has a chance of then being translated into an equivalent (perceived) "blue" on each of my printers (and each paper and each ink set).

 

Otherwise, the non-profiled instruction to "output 0,0,255" would merely give the maximum "blue" for my screen versus the maximum "blue" for my printer #1 (which may then be darker or lighter than my screen), and the maximum blue for my printer #2 (which may then be darker or lighter than my screen and the other printer) and so on. And when my file goes to an offset press, if they were to merely output a maximum "blue", they'd get yet another color entirely depending on the supplier of THEIR inks!

 

All were "blue", but all were different because of the limits of each device.

 

Profiling "tilts the scale" so to speak to match the available colors from different devices to best correspond to my chosen color on my editing device (which, of course, has been calibrated and profiled - right?).

 

Try this:

 

Assign: when there is no profile already describing the image file.

 

Convert: when the image file already has a profile but you must re-purpose the file.

 

For instance, AdobeRGB has MORE colors and is intended for printing, but sRGB has fewer colors and is intended for screen display.

 

Going to "publish" your image to a web page? You may want to assign or convert to sRGB and edit your pictures that way (on your calibrated and profiled display).

 

Going to "publish" your image to a specific printer/paper/ink setup? You may want to assign or convert to AdobeRGB and edit your pictures that way (on your calibrated and profiled display).

 

 

Back at ya, Robyn:

 

What are your REAL concerns here?

 

What is the source of your digital image file (camera, scanner?)?

 

What are you really dealing with regarding output (screen, printer, CMYK offset press?)?

 

What's your understanding "in simple terms (if that's possible)" of what the word "profile" means to you at the moment.

 

In other words, tell us more!

 

Tell us what you have found out so far in your research about the terms you ask about - including your copious reading the instruction manuals and help screens PLUS rudimentary Google searches,

 

Tell us what sticking point you have bumped up against in your current mastery of the meaning and application of "profiles", okay?

 

Thanks.

 

Click!

 

Love and hugs,

 

Pete Blaise peterblaise@yahoo.com http://www.peterblaisephotography.com/

[andrew_rodney1]

Numbers alone (like R23/G255/B67) don?t provide enough information to define a color.

It?s only an ingredient for the color (in this case, it?s very green, but how green?).

 

When you assign a profile, you give the numbers a definition such that Photoshop can

properly display (and convert) the color. Assigning doesn?t change the numeric values, it

only gives them a final meaning or definition by providing a color space to the numbers.

 

R255/G0/B0 is the most saturated red we can create. But the color is different in sRGB

versus ProPhoto RGB (or any color space). By assigning a profile (color space), we tell

Photoshop the scale of the R255. That is, R255 is more saturated in ProPhoto RGB than

sRGB yet they both share the same number (in this case R255). The number itself isn?t

enough information to allow Photoshop to show this value correctly. The number AND the

color space is key. Assigning a profile provides the number with the scale of the color

space.

 

Convert actually alters (changes) the numbers in a document. When you convert from RGB

to CMYK, or you convert from Adobe RGB (1998) to Epson 2400 glossy paper, you?re

changing all the numbers as well as assigning the new color space (Epson 2400) to the

file.

[andrew_rodney1]

--<For instance, AdobeRGB has MORE colors and is intended for printing, but sRGB has

fewer colors and is intended for screen display.

 

Actually no, there are not more colors. The scale is different (we can say the saturation is

different). But an 8-bit file in Adobe RGB (1998) doesn?t have more colors than an 8-bit

file in Adobe RGB (1998).

[photom]

Assigning a profile assigns a set of adjustment numbers for various color definitions that require adjustment to match the output device. The original file numbers are not changed but the profile is associated with the original file and the two sets of numbers can be added together when required. The advantage here is that you can later use a different profile that may work better (or for a different output device) and not change the original file.

 

Converting the file calculates the adjustments and saves the net resulting new color numbers and does not save the associated adustment profile. The advantage is that it is simpler, avoiding the confusion of handling an associated profile that the device must be able to handle. Some printers may not handle color profiles very well. Sending a converted file and turning off color management may be the cleanest way to get the desired output. I usually save my original file but convert just prior to printing and send off the converted file.

[robyn_geering1]

Thanks for your responses here. I think I've got it. I have just bought a digicam, and the cameras profile has been set at sRGB. I have just changed this to Adobe RGB (98), but you are saying that I still need to assign a profile, Adobe RGB (98)in photoshop regardless, for the reasons given. I also understand the reasons all of you are giving to convert, BUT I am currently reading a book called Adobe Photoshop Studio techniques, by Ben Willmore, and he states that if you plan to manipulate an image, than you need to convert to working RGB. My question is why. Why can you not just assign Adobe RGB (98) and work (manipulate) the file as is. What happens if I was to manipulate a file that I had assigned Adobe RGB, as opposed to converting to working RGB? Hope this makes sense.

[andrew_rodney1]

If the camera is set to either sRGB or Adobe RGB (1998), the question is, does some info in

the file tell Photoshop this? Most cameras do not embed a true ICC profile so Photoshop

doesn?t know the meaning of the numbers and you need to use the Assign Profile

command. Some cameras embed EXIF data that tells (or attempts to tell) Photoshop how

you set the camera matrix to produce a color space. Set your color settings to US PrePress

defaults. With the warning check boxes on, Photoshop will always alert you if the file being

opened has an embedded profile or not and further, if that embedded profile matches you

working space (the RGB profile you?ve set above). With a missing profile dialog, you?ll need

to use the Assign Profile command to tell Photoshop the file is in Adobe RGB (1998)

assuming that?s what you set on the camera. All files that are NOT in Adobe RGB (1998)

but have a profile will pop a warning. You can decide at this point if you want to work with

the embedded profile or convert to your working spaces.

[robyn_geering1]

Tom, you say that some printers do not handle colour profiles very well, so turning off the colour management and sending a converted file may give you the cleaned results. How do I turn off the printers colour management? Thanks