Re: Soft-proof copying in Photoshop - colour management 101
Re: Soft-proof copying in Photoshop - colour management 101
- Subject: Re: Soft-proof copying in Photoshop - colour management 101
- From: Mark Stegman <email@hidden>
- Date: Tue, 30 Jul 2013 13:30:20 +1000
David,
I drafted this response to an earlier email from David and I thought it might help with his current problem as well. Like Steve it is colour management 101 and it IS important but it never ceases to amaze me just how many users have yet to come to terms with it. Read on...
As Karl said you can use the Eyedropper tool to see the values but you can also use the Color Sampler (hidden under the Eyedropper). You really haven't supplied enough detail as to the exact workflow. I assume that you have exported your Raw image as an RGB (probably Adobe RGB 1998) and that you are using the Proof colors option to "apply" your custom "paper" (printer?) profile. If this is what you are doing then the values will not change. Not until you Convert the image to your profile.
It seems to me that you, like so may others, have not yet come to terms with the Adobe colour management implementation. A simple exercise can help.
Start by using an image with a wide gamut ( a range of different saturated colours). Select 4 different points using the Color Sampler ( I wish Adobe would give us more but I won't go into that). Monitor the changes to the values as you evaluate the difference between Assign Profile, Convert to Profile and Proof Colors. Note the values will have 'before' and 'after' side by side when the Assign Profile dialogue is open. This is a curious option here as the numbers do not change UNLESS you change the colour mode readout in the Info palette to Lab (click on the eyedropper symbol in the palette). If you save the image the sampler points will be saved with it but they will only appear when you are using the Color Sampler tool.
Select a different colour space in the Assign Profile dialogue and turn the Preview option On/Off to observe the change in appearance while the numbers remain static.
REMEMBER THIS - Assign Profile will change the appearance and preserve the numbers while Convert to Profile will change the numbers in order to TRY and preserve the appearance. Before my learned friends on this forum jump in I would like to add that this has some important qualifications.
Assign a profile to see what the values in your image will produce when rendered on a different 'device' or in a different colour space. The (device dependent RGB or CMYK) numbers do not change however, the Lab numbers will as they define the appearance. As these are usually 'under the bonnet' you will not see them... unless you go looking.
The accuracy of the rendering on screen will depend on the quality and gamut of your monitor as well as how recently it has been calibrated and profiled. Of course, when you are assessing the print one of the most important things to be aware of is the viewing conditions which need to be standardised and consistent with the profile you are using. Note that you can only Assign profiles within the same colour mode - RGB or CMYK (as the numbers cannot change). As there is no conversion, there is no option to select a Rendering Intent and other options available when using Convert to Profile.
Use Convert to Profile when you need to change the numbers to meet some other purpose. This is usually done at the last moment and very often NOT AT ALL in image preparation as it locks in a final destination printing condition which may not be suitable for other output purposes. Image preparation in Prepress may still edit in CMYK as they know the printing condition the file is destined for. Note that Convert to Profile allows you to change within the same colour model OR from one colour model to another e.g. RGB to RGB or RGB to CMYK. This MAY result in no change in appearance, especially when the destination profile has a larger gamut than the source however, if you have images with highly saturated colours that are outside the gamut of the destination profile the appearance will change and some clipping will occur when using a colorimetric Rendering Intent.
The Proof Colors option allows you to PREVIEW the result of a conversion WITHOUT converting and enables the image editor to predict the eventual result while still editing the image in RGB mode, retaining access to the wider range of tools, techniques and effects that are available.
You don't say whether your custom 'paper' profile is an RGB printer profile or a CMYK press profile. I suspect the former. RGB printer profiles will be only available in the list of profiles when using Assign Profile and your image is in an RGB colour space. CMYK press profiles will only be available when your image is already in the CMYK colour mode.
I'll stop there.
Hope this helps.
Mark Stegman
On 30/07/2013, at 11:12 AM, Steve Upton <email@hidden> wrote:
>
> On Jul 29, 2013, at 5:41 PM, Spinnaker Photo Imaging Center <email@hidden> wrote:
>
>>
>> Hi Steve. Please comment on what I am doing. I was never taught this in seminars I attended.
>>
>> You might have noticed my earlier question about soft proofing and attempting to use some kind of numbers to have the soft proof out of the printer, look like what I see on the monitor.
>>
>> One of the suggestions was (and I used this suggestion today) in PS CS5, go to edit > convert to profile and choose the custom .icc printer/paper/ink profile I created. These appears to to give the same looking image as soft proofing.
>>
>> Please comment. And I thank you for all you do for color community.
>
> Hi David,
>
> This is, as you suspected, Color Management 101-level stuff. But that doesn't decrease it's importance - or it's ability to confuse.
>
> Mainly, don't forget that RGB and CMYK are NOT colors, they are device-flavored settings. For quick review see <http://www.colorwiki.com/wiki/The_Color_of_Toast>
>
> Photoshop makes it easy to soft proof what something might look like (colors) when printed to a specific device. It does this behind the scenes though, so unless you plan for it (different dropper settings), dropper values are still your file's original device values.
>
> Converting to your output profile "manually" will certainly give you your final output numbers but it's fairly dangerous as accidentally saving that file will forever relegate your file's gamut to that of your printer. ugh! So tread carefully or use a duplicate of your file.
>
> When dealing with non-colormanaged output destinations (like the web), it is wise to convert "by hand" in Photoshop as I explained in my previous email. The path I suggested, file->outputProfile -> sRGB is similar to Photoshop's soft proofing mechanism though PS would end in your monitor profile rather than sRGB. The main difference is that your file is now permanently in color-effected sRGB. Color-effected meaning that it captures the effect of printing to your special-case output device and it's in sRGB for the web.
>
> I hope this clears things up.. if not, ask away!
>
> regards,
>
> Steve
>
>
>
>
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