Assign or convert....

What a rough week... Heck it hasn't ended yet.

So it all started this last week after I shot engagement images. I imported the images using Lightroom 1.4 and then looked at the images in Adobe Bride. I adjusted all my images using Camera Raw 4.0 and then converted all the images to tiff (Adobe 98, 16bit). I did all final adjustments in Photoshop. After I'm done I always add a copyright to all the images and "convert," in this case "assign..."(oops) to sRGB and make it Jpegs for the online gallery. Sounds simple enough (I used an action to do all this).

After I was done I looked in PS and they looked fine, built my gallery, and uploaded to my server and checked it. This is when it went down hill. All the images were over-saturated. So everything came spiraling down.... What happened? What did I do wrong? Was it my monitor? Did I do something wrong when changing the profile to sRGB? Was it out of my control?

I had to go through multiple steps to find a solution. Below is the first step to finding it:

I don't know why I never thought about it, but why is there two ways to get a profile on an image? I vaguely knew it was there but always thought they were the same thing.

So do you "assign profile..." or "convert to profile..."?

Well in short always "convert to profile" when you are going from one profile to another. Why you ask? Then read on!

Assign profile only changes the preview while convert changes the values in the actual file.
Also if your file is untagged you can use assign profile.

This is not saying that sometimes you can't break the rules and be creative but if you are just trying to go from one color space to another use "convert to profile."

So lets "convert to profile..."

You have a dialog box open up with a few options...


This perplexed me.... Not only does it ask me what profile I would like to use but what rendering intent I wanted to use and what engine. That freaked me out. In my world when I thought about rendering intents I thought printing profiles.

But once I relaxed, I started to think about it.
Think about it as your output. Whatever that output is, whether printing, or web page.

SO that also got me thinking don't ever change a profile until you have to and if you don't, don't. It hurts the file, you lose data. For example, (not the same but will give you the idea). Would you go from a tiff to a jpeg and then convert back to tiff or worse yet resave the jpeg? No! because you know that once you lose data its gone!! It can't come back.

When you go back to a larger color space, all it does is put the same information from the small color space under an umbrella that is bigger than you need now.

Now when you convert you get the opportunity to change the profile using different algorithms, most of the time Perceptual or Relative, or do you? When converting from a working space to working space(simple matrix profile) the only intent it will use is Relative Colorimetric even if you choose perceptual. *This doesn't apply to printing profiles.*

Also, what engine get used? Adobe(ACE (Adobe color engine)) or Microsoft ICM (or if you use a mac you will have their option.) Choose Adobe(ACE)! From my understanding Abode(ACE) has enhanced support for black point compensation(another topic all by itself.)

by default black point compensation(BPC) and dither is checked. I always leave them checked because in this example it uses Relative Colorimetric to convert the profile.


But to help clarify:
"Use BPC" should be used for relative and not for perceptual. This isn't a hard fast rule, though. You can make your own decisions. Perceptual already maps the white and black so you typically don't need it.
"Use Dither" is only an option when changing color space in 8 bit not 16bit. It helps keep the colors image transitions smooth.

SO now that I know that I need to convert a profile and how! I can create an action and have correct color output, but darn if I didn't run into more problems.

I will delve into my solution or at least what the problem was next week. If you have any questions or would like to discuss this with me please call or email.