icc profiles - when applied?

[bugbear]

I have successfully been using IM 6.3.5 to perform ICC profile manipulation, using commands of this form:

convert orig.rgb.tif -profile a.icc -profile b.icc new.rgb.tif

The orig.rgb.tif has no embedded profile, so "a.icc" is an assumption.

Since my "orig.rgb.tif" files are quite large, I would like to subsample them.
Since my cpu is precious, and ICC manipulation is expensive, I would like to subsample, then apply the ICC.

But there is no (obvious to me) command that applies the profile! Indeed, although my
present command works, it's far from clear to me how the two -profile options are
acted on (i.e. correctly applied to source and dest).

I think this is more a command line interpretation question than an ICC one.

If anyone can advise, either specifically in the case at hand, or on command line handling in general, I'd be grateful.

BugBear

[fmw42]

seems to me that if your input has no ICC profile, then you could

convert input -resize ... -profile a.icc -profile b.icc result

but I am not an expert on profiles.

see http://www.imagemagick.org/Usage/formats/#profiles

you could also add -strip after the input to remove all info and profiles and then just use the two profiles assuming you know which ones are appropriate.

By the way,

identify -verbose input

will list out the profiles you have in your image

[bugbear]

It's not profiles (per se) that causing me trouble. It's the "when" of command line parsing/processing.

Is "-profile" an option or a command? What does it apply/refer to?

BugBear

[fmw42]

It is an command option as opposed to a setting option. see http://www.imagemagick.org/Usage/reference.html

[anthony]

The term is operation.

If no profiles are present it saves the given profile as image meta data (a hidden change or setting)

However if a profile is already present it modifies the image data to transform the colors from one profile into the other profile before replacing the original profile with the new one.

[bugbear]

Excellent; I think adding the information from this thread (thanks to all) to this:

http://www.imagemagick.org/Usage/formats/#color_profile

Tell me enough to control my destiny.

It's a bit more complex than I'd hoped (and I mean just the "applying"
syntax, not the profiles themselves), but manageable.

BugBear

[anthony]

It is already present in that area.

[bugbear]

It is already present in that area.

I disagree; the language in that section varies all over the shop, and didn't give me clear and unambiguous information on which to proceed.

For example:

>> If there is no embedded profile then the first "-profile" is the input profile. A second "-profile" then defines the output profile.

The word "defines" is clearly problematic.

>> The second "-profile" given, is the output profile.

Is this applied at "output" (i.e. file generation) or immediately?

>> This sets the resulting image to a CMYK USCoat.icm profile.

Setting a profile is different from performing a profile conversion on the image data; one might (quite reasonably) want to "set" a profile on an image which is known (due to context), but doesn't carry a profile e.g. a digital camera for which one has generated a profile.

Clearly, all the examples in that section of the manual "work", but I don't think the overall information is clear, especially to a newcomer.

This has all sounded negative, so I'll end by saying - thanks to all for ImageMagick, including the (ICC stuff), and thanks to all for your help in this thread.

BugBear

[anthony]

Yes I suppose it is. More because it is not something I use myself.

Would you care to re-write the section?
Just copy the HTML re-write the parts, and mail it to me.

[bugbear]

Yes I suppose it is. More because it is not something I use myself.

Would you care to re-write the section?
Just copy the HTML re-write the parts, and mail it to me.

Heh. I asked for that,didn't I

My writing isn't the best, but I'll try to find time, and write English.

BugBear