why are my sRGB pics changed to adobe RGB by Aperture

My camera is set to take sRGB pictures. Yet, when I import the picture in aperture the EXIF data shows then as being -color model = RGB - and -profile name = adobe RGB.
Commercial printers use the adobe sRGB color space to print digital picture. If apple is changing my pictures to adobe RGB, it might explain why my aperture prints are coming back from Kodak and Fuji underexposed even though they print just fine on my home printer.

powermac G5

Posted on Dec 31, 2008 7:38 PM

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11 replies

Jan 1, 2009 6:35 AM in response to taronger

If you shot RAW, RAW images have their own color space and Aperture handles all RAW in their own unique way - think of Adobe RGB as the working space in Aperture.

You may also be looking at image versions exported from Aperture - in that case the export preset you are using is set to convert to Adobe RGB - just create a new one that converts to any space that you would like - this is probably your issue with sending out images to be printed.

RB

Jan 1, 2009 12:02 PM in response to taronger

Have you calibrated your monitor? Note if the luminance value is set too high on your monitor, prints (from a printer or from a lab) will come back too dark. You must set your monitor luminance properly... I believe 120 is the target value which is about 1/3 brightness on my 30" Cinema display. If you're not using a hardware calibrator you really have no hope of getting good results.

As far as color space... if you shoot RAW, then the value set on the camera of sRGB or Adobe RGB has no meaning. RAW files have no color space, and Aperture internally uses its own proprietary color space. On export, it will apply sRGB or Adobe RGB depending on your export settings. You need to check this; you can set it to sRGB on export and for JPEG exports for web (and usually for print), that's what you should do. Still, this typically doesn't result in prints being too dark... more often the colors will be under/over saturated or off in tint, rather than under/over exposed with a color space mismatch.

Jan 1, 2009 2:56 PM in response to William Lloyd

On export, it will apply sRGB or Adobe RGB depending on your export settings.


This advice should come with a warning. To understand the warning, launch the Apple ColorSync Utility and create a gamut comparison.

First, open the Profiles list and in the Profiles list open the Disclosure icon for RGB data space profiles, which will show you as well type MNTR Monitor as type PRTR printer profiles with data space RGB.

Select sRGB Profile and the CIEL a*b plot opens on the right. Open the Disclosure icon for the CIEL a*b plot and select Hold for Comparison.

Second, open the Disclosure icon for RGB data spaces and select a high gamut Large Format Inkjet printing proess, or open the Disclosure icon for CMYK data spaces and select an ISO 12647 standard offset printing condition for offset configured in Heidelberg PrintOpen.

For instance, if you select ISO 12647 for glossy paper you will find when you hold and turn the interactive gamut comparison that sRGB is incapaple of defining cyans and greens that can be printed in ISO 12647 for glossy paper.

If you do not have the colour defined in your source colour space, you are incapable for reproducing the colour in your destination colour space - even if the destination colour space is capable for forming that colour.

If sRGB is too small for standard offset, it is much, much too small for large format inkjet on glossy papers. This is the reason sRGB is not recommended as archival space, and as interchange space on one and only one condition.

In so far as Windows systems are colour managed, they have had a simplified colour management system that does not call for computing capacity to calculate colourants.

Colour devices (scanners, camers, monitors, printers) have been predefined as having one and only one colour gamut, that is, the colour gamut of HDTV for a cathode ray tube monitor.

If you want to share colour images or colour illustrations in a non-colour managed world, then sRGB is a sensible solution since it simulates the default colour space of a display.

But by the same token, if you work in a colour managed process where you have control over the maximum gamut your colour devices are capable of, don't every use sRGB.

Best,
Henrik Holmegaard
technical writer

Reference ISO 12647 Profiles:
http://www.eci.org/lib/exe/fetch.php?id=en%3Adownloads&cache=cache&media=downloa ds:iccprofiles_from_eci:eci_offset2008.zip

(Note: A decade ago FOGRA posted both PrintOpen and ProfileMaker profiles for ISO 12647. The politics of prepress and printing have left only PrintOpen profiles in public space. The ECI archive holds high resolution profiles with maximum interpolation precision - not low resolution profiles.)

Jan 1, 2009 4:51 PM in response to Henrik Holmegaard

Wow, that's a lot of technical detail.

But, for the most part, it's irrelevant.

Because, if you display something on the web, you're displaying to an environment that is, by and large, not color managed. Pretty much every browser but Safari (which is now 9% share, it looks like) assumes sRGB. So if you put out Adobe RGB to the web, it's not going to be displayed properly. And... if you're throwing something on the web, gamut clipping just isn't that big of a deal. You're not selling the images in that form.

If you're sending it somewhere to be printed... the FIRST thing you should ask is what format they want it in. If they can handle Adobe RGB, then by all means go that route. But most printers expect sRGB, so sending them Adobe RGB by default pretty much ensures you'll get bad results.

As far as printing to an inkjet printer... why send it to be printed via inkjet? If I were doing this, I'd probably send a TIFF to someone as opposed to a JPEG.

Jan 1, 2009 5:00 PM in response to William Lloyd

Not that it's relevant but Firefox3 has color management as well - you just have to turn it on. It actually works fairly well. As long as we are all ranting about it now here is my short take on it.

[Color Management For People that don't care|http://photo.rwboyer.com/2008/04/color-management-and-other-stupid-interne t-tricks>

Yea yea I know - it doesn't address working space, clipping, blah, blah, blah - if you care about that you already know it or can find it out pretty quick, it's intended as a rant against some "common" wisdom that is espoused all over the place that way too many people follow blindly.

RB

Jan 1, 2009 5:04 PM in response to rwboyer

Yes, you can turn color management on in Firefox 3. But, it's off by default. How many people do you think are turning it on? My guess: << 1%. Unless someone has the insight to say "Hmmm... that flower looks undersaturated... I wonder if it's in the Adobe RGB color space... Firefox lets me change that let's experiment!"

😉

Nice article. SmugMug also has a number of extensive articles on color management and formats to send to the printer. My recollection is that they said "Send us files as sRGB. It's almost always the correct option." I suspect their labs (EZPrints) assume or can only print sRGB gamut.

Jan 1, 2009 5:24 PM in response to William Lloyd

Pretty much every browser but Safari (which is now 9% share, it looks like) assumes sRGB.


Technically, sRGB is intended as a simplified colour management system that supports one and only one colour gamut, sRGB.

Since sRGB is expressable in the ICC file format, sRGB can become a source colour space in a standard ISO 15076 (: ICC) colour matching session.

You are assuming that HTML is presently, and will permanently stay, a medium that is not completely colour managed. Neither assumption is correct.

If you're sending it somewhere to be printed... the FIRST thing you should ask is what format they want it in. If they can handle Adobe RGB, then by all means go that route. But most printers expect sRGB, so sending them Adobe RGB by default pretty much ensures you'll get bad results.


Sorry, but this is technically incorrect. The colour spaces expressed in ICC type MNTR Monitor profiles for sRGB, AdobeRGB and other matrix-based linear colour spaces introduced in Photoshop 5 are simply SOURCE colour spaces in ISO 15076 colour matching sessions.

Just as sRGB has problems in cyans, AdobeRGB has problems in yellows. You can capture yellows in EktaChrome that AdobeRGB cannot contain - they are clipped in converting from the source colour space of your scanning condition into the linearised AdobeRGB space for colour correction.

What a prepress manager wants is correct colourants for the printing condition. To get that, a prepress manager creates an ICC type PRTR Printer profile for the calibrated condition of the printing system, ensuring that the printing system can be constant over time, keeping to the calibrated condition that was characterised in the colour test chart(s).

Any object in any position on any page should be processed through the same colour-colourant conversion in order to ensure that the inking is correct for the intended colours and the intended graybalance and the intended shadow, midtone and highlight treatment.

No professional printer operating an offset press expects sRGB since sRGB cannot contain the colours that are reproducible in a standard ISO 12647 printing condition on anything above newsprint and lowly gray magasine paper.

Technically, the ICC frontend for a production PDF-to-PostScript RIP parses the incoming data looking for ToCIE colour space specifications per object, and converts into the destination ICCBased OutputIntent set in the PDF/X-3 printing master. The ICC frontend does not default to any particular size or shape of source colour space, it simply scans for source ToCIE spaces. With regard to device colour, there are various things the prepress manager can do in the ICC frontend. Basically, just as in Apple Preview a default source ICC space is assigned to device dependent RGB (: Generic RGB Profile), the prepress manager can set a source of her choosing. This source might be sRGB, since sRGB is common, but the point is that there should not be any untagged RGB in the printing master in the first place. Certainly not if the photographer cares about his work and has a clue about colour management -:).

If you want to work with an archival space that can hold printable colours, here are some suggestions. Joseph Holmes has EktaSpace which is available at his site (www.josephholmes.com). And a group of people including Dietmar Fuchs created PhotoGamut ( http://photogamut.org/E_Founder.html).

As far as printing to an inkjet printer... why send it to be printed via inkjet?


Professional photographers often sell prints of their photographs. To do so, they print their photographs on their inhouse large format inkjets using archival inks and papers they carefully choose for maximum gamut.

Cheers,
Henrik

Jan 1, 2009 8:09 PM in response to taronger

Thank you all for helping me to understand the intricacies of RGB - yes, you are correct, the pictures I am working on were shot in RAW format. However, I only switched to RAW after encountering the same dark printing problem with pictures shot as JPEGs.
After reading your postings, I am not sure that I have specified the correct sRGB settings to export out of Aperture.
Under preferences---->"external editor format" my current setting is "TIFF - 300DPI". (I should probably increase the DPI) - sRGB is not offered as an option here.
under export-------->"export preset" the settings are
JPG- original size
image quality -12
size -original size
DPI -72
gamma adjust -0
colorsync profile -sRGB
under view----------> proofing profile - I show HP D7300 Prem plus photo ( for my printer and paper being used)
Although these settings work fine with my inkjet printer, it may be that I need to change them when creating an export file for printing by a photo shop. I am not well versed on this topic and your input is appreciated.

Jan 2, 2009 1:15 AM in response to taronger

my current setting is "TIFF - 300DPI". (I should probably increase the DPI) - sRGB is not offered as an option here.


TIFF stands for Tagged Image File Format. The format was originally owned by Aldus and was acquired by Adobe when the companies merged in 1994. TIFF is the default interchange file format and archive file format for photographic images. The file format supports embedding of an ICC source profile as a tag. 300 dots per inch is adequate for rasterisation to professional offset printing. The conversion calculation from DPI to LPI can be found in prepress handbooks.

"export preset" the settings are
JPG- original size
image quality -12
size -original size
DPI -72
gamma adjust -0
colorsync profile -sRGB


This configuration supports export of screen resolution photographic images, with lossy compression. A conversion takes place from the source colour space that describes the RGB colourants in Aperture to the destination colour space sRGB. The idea behind sRGB is, as explained, that is a common denominator for the default calibration of a Sony CRT / HDTV. So you get a decent match, provided the user has not changed the state of the display, and provided the display can in fact be decently described by preconditions of sRGB.

proofing profile - I show HP D7300 Prem plus photo ( for my printer and paper being used)


Yes.

Although these settings work fine with my inkjet printer, it may be that I need to change them when creating an export file for printing by a photo shop.


Sending your printing shop 72 DPI sRGB is simply silly. If your colour capture space and colour correction space support hues and chromas not supported in sRGB, your printing shot is in principle unable to reproduce those colours. It's like throwing money out the window. It makes no sense, since the point and purpose of the ICC framework is to give you access to the maximum gamut your colour device is capable of forming.

/hh

Jan 3, 2009 8:41 AM in response to Henrik Holmegaard

Hello Henrik - Thank you for your answers - I do not have any problems with the color rendition of pictures printed either on my printer or by a commercial photo shop. My only concern is that the pictures printed by photo processing shops are too dark and look as if they were underexposed.

it does seem unrealistic to have my export presets set to 72DPI, and I will change that to 300DPI.

Thanks for your recommendation

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why are my sRGB pics changed to adobe RGB by Aperture

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