Using Color Profiles

brettdog:

For ordering books, calendars and prints from iPhoto the sRGB profile is recommended as that's what Apple uses. Doing your own printing may mean a different profile depending on the your preferences. The Adobe profile is a much larger one than sRGB. You can compare them with ColorSync Utility.

I have sRGB setup for all devices, Photoshop, etc. and that seems to work well for me. It seems better matched for my Epson printer than for my Canon. I don't have the gamma reset to 2.2 and I'm sure that's why photos that look good on the monitor are much brighter on a TV screen when added to an iDVD project, burned and played that way.

You can do a Google search for color management and see what that turns up. I'm sure there are a number of good informational sites on the subject.

Questions.
1. In Image Capture, what profile should I use in the
add profile during import option?

The most "correct" profile to use here is "Camera RGB" if your camera is using the sRGB Colorspace. If your camera supports Adobe RGB (1998) and you are using that then the profile doesn't matter as your camera should have already embed it.

-- Start technical explanation why --

The reason for using "Camera RGB" over "sRGB Profile" is because "sRGB" is an output profile that approximates the supported colorspace of most computer displays and has already been applied to the image by your camera so that it will appear "correctly" when viewed unmanaged on a PC (with a display gamma of 2.2).

Basically this is the camera manufacturers way of avoiding having to educate users about colour management because the images look fine without any, at least on a PC.

If you were to assign "sRGB Profile" to the image, you are effectively applying the sRGB (output) colour compensation twice (which isn't 1:1 RGB), so the image's colour will actually look slightly different when it is viewed using a non colour managed application.

The "Camera RGB" profile on the other hand represents a true 1:1 RGB mapping with a 2.2 gamma correction profile, so it will allow any mac or PC user, regardless of the display gamma to view the images as they were intended by the camera. This is why iPhoto applies the "Camera RGB" to images it edits that were originally untagged, to ensure that they continue to appear consistently despite the display gamma.

--- End long winded technical description ---

2. How do I tell what profiles were used on the
previous imported photos?

Drag an image to Preview and open the Get Info inspector, if there is a profile assigned to the image it will appear next to "ColorSync Profile"

3. Can the profiles be changed or added to existing
photos in iphoto?

Probably, you might need to use Automator or something. I haven't tried to do this personally.

I have "Add ColorSync Profile" enabled in iPhoto and it adds the "Camera RGB" profile to untagged images for me on import.

Seeya...Q

TheQ,

Testing for understanding,

The camera is applying the sRGB profile to the
captured image and storing the jpeg to the memory
card, but the profile is not embedded in the image?

Correct. The colourspace is usually specified in the EXIF data by the camera rather than actually embedding a profile if sRGB is being used.

Currently only two possible EXIF values for the colourspace are defined, they are "sRGB" and "Unknown". If your camera uses something like Adobe RGB (1998) it will (or at least should) set the colourspace in the EXIF data to unknown and embed it's own profile.

The Camera sRGB profile is designed to work with
images that have the sRGB profile already applied.

Yes, in effect. It is designed to work with any untagged RGB image that is intended to be viewed on a PC (gamma 2.2) monitor.

Embedding the Camera sRGB profile in the image when
importing with Image Capture will allow color
management aware applications to apply this profile
and the image will look the same on any system

Provided that the systems viewing the image are either using a viewer that is ICC aware, or their screen is set to use a 2.2 gamma.

hopefully printed the same as the displayed
image.(Printing service ie Kodak).

Hopefully, however some print services with "enhance" images before printing so that your prints like "better". Something you may need to investigate further if you aren't printing the images yourself.

However, non aware color management applications will
display differently on 1.8 vs. 2.2 gamma and the 2.2
will more closely resemble the actual image.

Yes.. Camino isn't ICC aware and can be used for a simple test on the Mac. If you recalibrate your display to 1.8 gamma and open the image in both Camino (or Firefox) and Safari you will see that they appear differently. Open the same images with the screen calibrated to 2.2 gamma and they should look the same. (Remembering to restart Safari between screen recalibrations)

A while back I added the Nikon sRGB profile to a
number of photos with Image Capture and wanted to
know if it would be ok to change it to Camera RGB.

You could do this if you wish. You can use either Preview or ColorSync Utility to do this.

Seeya...Q

Embedding the Camera sRGB profile in the image when
importing with Image Capture will allow color
management aware applications to apply this profile
and the image will look the same on any system

Provided that the systems viewing the image are
either using a viewer that is ICC aware, or their
screen is set to use a 2.2 gamma.

Thanks for the great explanations. However I don't fully understand the point above. If it makes sense for iPhoto to assign the Camera RGB Profile, shouldn't one similarly assign Camera RGB Profile when using Image Capture to get the same results?

Also, some cameras seem to produce output with different profiles, like Adobe RGB 1998. In this case presumably iPhoto will mess things up by incorrectly assigning the Camera RGB profile if the real profile is not actually embedded in the file received from the camera - is that correct?

iMac G5, PowerBook G4 and iMac DV SE Mac OS X (10.4.4) Canon Powershot G6

Thanks for the great explanations. However I don't
fully understand the point above. If it makes sense
for iPhoto to assign the Camera RGB Profile,
shouldn't one similarly assign Camera RGB Profile
when using Image Capture to get the same results?

Yes, and this is the default profile that is assigned to a camera should you set it to embed one.

Also, some cameras seem to produce output with
different profiles, like Adobe RGB 1998. In this case
presumably iPhoto will mess things up by incorrectly
assigning the Camera RGB profile if the real profile
is not actually embedded in the file received from
the camera - is that correct?

Well yes, but it would mean your camera is very broken. If you set your camera to use Adobe RGB (1998) it will embed this profile into the image when the shot is taken, making it a "tagged" image. When you import the files to your mac ImageCapture/iPhoto will only assign a profile to "untagged" images.

Seeya...Q

Makes sense. Thanks again for the very helpful information. If it's not too personal a question can I ask where you get this from? I'd like to find out more myself.

Makes sense. Thanks again for the very helpful
information. If it's not too personal a question can
I ask where you get this from? I'd like to find out
more myself.

A combination of reading apple's documentation and experimenting with tools like ColorSync Utility and DigitalColor Meter.

Seeya...Q

Thanks yet again!

Folks,
I noticed that importing photos (into iphoto) from a DVD takes a long time when the "Add colorsync" option is selected under Preferences->Advanced

It takes approx 15-20 secs to import a single picture. With this option truned off it takes under 2 secs per picture. I am trying to understand why the addition of colorsync profiles adds this huge overhead. Is this normal?

Did the previous version of iphoto add colorsync profiles?

thanks

Questions.
1. In Image Capture, what profile should I use in

the

add profile during import option?

The most "correct" profile to use here is "Camera
RGB" if your camera is using the sRGB Colorspace. If
your camera supports Adobe RGB (1998) and you are
using that then the profile doesn't matter as your
camera should have already embed it.

Please explain if i'm wrong but if I extract the
Camera RGB profile from a photo in iPhoto (e.g.
by using an AppleScript) this profile is identical t
o Generic RGB, a RGB colorspace that is slightly
smaller than RGB. I do not understand how this is
an accurate "adjustment" for the images from
my camera.

-- Start technical explanation why --

The reason for using "Camera RGB" over "sRGB Profile"
is because "sRGB" is an output profile that
approximates the supported colorspace of most
computer displays and has already been applied to the
image by your camera so that it will appear
"correctly" when viewed unmanaged on a PC (with a
display gamma of 2.2).

sRGB is not an output profile. It is a color
space.

Basically this is the camera manufacturers way of
avoiding having to educate users about colour
management because the images look fine without any,
at least on a PC.

If you were to assign "sRGB Profile" to the image,
you are effectively applying the sRGB (output) colour
compensation twice (which isn't 1:1 RGB), so the
image's colour will actually look slightly different
when it is viewed using a non colour managed
application.

Can you provide a source for this info?

The "Camera RGB" profile on the other hand represents
a true 1:1 RGB mapping with a 2.2 gamma correction
profile, so it will allow any mac or PC user,
regardless of the display gamma to view the images as
they were intended by the camera. This is why iPhoto
applies the "Camera RGB" to images it edits that were
originally untagged, to ensure that they continue to
appear consistently despite the display gamma.

--- End long winded technical description ---

2. How do I tell what profiles were used on the
previous imported photos?

Drag an image to Preview and open the Get Info
inspector, if there is a profile assigned to the
image it will appear next to "ColorSync Profile"

3. Can the profiles be changed or added to

existing

photos in iphoto?

Probably, you might need to use Automator or
something. I haven't tried to do this personally.

You can use the scripts provided for ColorSync in .
/Library/ColorSync/Scripts

I have "Add ColorSync Profile" enabled in iPhoto and
it adds the "Camera RGB" profile to untagged images
for me on import.

Seeya...Q

I hope someone can explain al this!

Regards,
Thomas

I'm probably still missing something but when I import photos that have the EXIF color profile info set as sRGB, iPhoto still tags them with the Camera RGB profile. Why? My camera (Nikon D50) sets that EXIF color profile information for a reason.

If I choose to not import the images into iPhoto's library, but reference them instead, the profile info is retained (good). But, as soon as I go ahead and edit the image in iPhoto, it's tagged with the Camera RGB profile (not good).

Hopefully this'll change in future revisions.

A lot of user inquiries on these boards as to why Apple embeds the Camera RGB Profile instead of the sRGB profile in iPhoto for untagged images, refer the questioner to this thread. I have even been referred to this thread repeatedly from elsewhere on the web.

That's very unfortunate, because the following explanation (seen above) is completely bogus:

-- Begin BOGUS technical explanation --

The reason for using "Camera RGB" over "sRGB Profile" is because "sRGB" is an output profile that approximates the supported colorspace of most computer displays and has already been applied to the image by your camera so that it will appear "correctly" when viewed unmanaged on a PC (with a display gamma of 2.2).

Basically this is the camera manufacturers way of avoiding having to educate users about colour management because the images look fine without any, at least on a PC.

If you were to assign "sRGB Profile" to the image, you are effectively applying the sRGB (output) colour compensation twice (which isn't 1:1 RGB), so the image's colour will actually look slightly different when it is viewed using a non colour managed application.

The "Camera RGB" profile on the other hand represents a true 1:1 RGB mapping with a 2.2 gamma correction profile, so it will allow any mac or PC user, regardless of the display gamma to view the images as they were intended by the camera. This is why iPhoto applies the "Camera RGB" to images it edits that were originally untagged, to ensure that they continue to appear consistently despite the display gamma.

--- End BOGUS technical description ---

The reason this is completely bogus is that whether you embed a profile or not, the image data itself is left completely untouched. It is untransformed in any way. This INCLUDES the moment the camera embeds its own profile information.

In other words, by labelling your image as an sRGB image, your camera DID NOT CHANGE YOUR IMAGE AT ALL, it just provided a tip to your computer on how to transform the image to get the right colours out of it. iPhoto, by ignoring this tip and instead embedding the Camera RGB Profile, simply replaces one tip with another. THIS DOES NOT CAUSE A DOUBLE-TRANSFORMATION, OR SHIFTING SOMEWHERE AND THEN SHIFTING BACK, OR ANY DOUBLE-APPLIED EFFECT WHATSOEVER.

THERE IS NO SUCH THING AS DOUBLE-APPLYING A COLOUR SPACE.

It's like if I tell you twice to interpret my comments as ironic. The fact that I told you twice doesn't make my comments doubly ironic. It just means that you've been told twice. PROFILES ARE NOT A TRANSFORMATION -- THEY ARE JUST AN INTERPRETIVE TIP. Thus, there is no such thing as OVERapplying a profile. It can't happen, period. The second profile just replaces the first which disappears having left no trace upon the picture data whatsoever. (There is a such thing as double-CONVERTING a profile but that's a whole different animal that is completely unrelated to iPhoto.)

Ergo, if iPhoto were to embed sRGB profile into images already recommended for sRGB, THAT WOULD BE PERFECT! This does not result in any degradation. The fact that Apple chooses to use a different profile is simply because out of the box, most Macs are friendlier to 1.8 gamma profiles than 2.2 gamma profiles. In other words, people will complain less.

That's it, that's the only reason. Enjoy.

Mac OS X (10.4.8)

Also I would like to add that DESPITE the fact that most camera manufacturers tag their images "ColorSpace: RGB" in the Exif data, most consumer camera preview LCDs ARE UNCALIBRATED, not to sRGB nor to anything else, and they are CERTAINLY not showing you your picture with the so-called "sRGB ColorSpace" taken into account.

So if you think you are looking at your pictures in sRGB on your camera's LCD, you are probably mistaken.

My Canon Powershot A75, for example, labels all its images with a gamma of 2.2 (i.e. sRGB), and yet the LCD on the camera happens to have an almost identical gamma to my iMac LCD.

So basically, this entire discussion is moot, because the so-called "standard" sRGB is not a standard at all in the camera world, and cameras will happily label their images sRGB while providing you with LCD images that are as far away from that as possible.

The result is that even if my entire system is completely, perfectly calibrated to sRGB, my images will all look way darker.

My solution was to just apply the damned iMac LCD profile to all my images, since visually it provides to the closest results of all my profiles (makes sense doesn't it -- it's an LCD), and all the "experts" who recommend doing things by the book? I laugh in their faces.

Let me say what most of you know but are struggling to find a way around.

It is completely pointless to try to standardise any workflow to the sRGB standard used in cameras, because this standard is a ruse. It doesn't exist. It's a fiction. It's a labelling standard, NOT an engineering standard.

All the camera manufacturers just build it however they like and then label it sRGB.

This is a fact.

And if you want to get the colours you're looking for, you will be wisest to completely ignore the profile on any image tagged 'sRGB'.