Hi Bob,

The best way to answer the question (assuming you are not using a custom camera profile) is to hover your mouse pointer over a thimbnail of one of your raw images.
The color space that is used will be shown in the "hotbar" below the thumbnails.
See the screen snaps attached.

In the Edit/ Raw Options menu, you can select your Raw color space from Adobe rgb  to a camera specific or an sRGB color space.

Hope this helps.
Fred

Just to add a comment;
Some editors like PaintShop Pro have a so called "working colour space" and any image opened in that program is usually converted to that colour space.

QU does not work like that - it uses the colour space of the image, defined by a exif tag, raw image profile or, as priority, an embedded profile. In the event of no defined profile QU will default to sRGB - which may not always be correct if it's come from another program where the profile has not been embedded.
When a raw image is converted in QU, you decide what colour space it is converted too and the profile is embedded.

Fred has explained how to determine what profile QU is "seeing" and QU, when printing, converts from that profile, whatever it is, to the printer profile.

Without knowing the process being used to create a printer profile with that open source software, it's difficult to know why a "source" profile is required.
DDI Profile Prism profiling software does not require such information and printer targets are printed with colour management turned off, as is required with other profiling software.
Terry

I have used Argyllcms for a long time, and I must admit that I don't understand all the technical aspects of color management.  I understand that I want to print my targets without color management specified in the driver, and that when I've built my profile, I specify that in QU and it's applied to the final print whether it's printed locally or sent off to the lab.

I've had a lot of success with Argyllcms and thought I would ask about this as I was reviewing the workflow for creating the profiles.    One of the options that is shown in the "typical usage" instructions is the -S which is a source profile.   The explication is rather complex and I must admit I don't really understand it.   I believe Mike would understand it.

(excerpt from http://www.argyllcms.com/doc/Scenarios.html#PP5)

"Where the resulting profile will be used conventionally (ie. using collink -s, or cctiff or most other "dumb" CMMs) it is important to specify that gamut mapping should be computed for the output (B2A) perceptual and saturation tables. This is done by specifying a device profile as the parameter to the colprof -S flag. When you intend to create a "general use" profile, it can be a good technique to specify the source gamut as the opposite type of profile to that being created, i.e. if a printer profile is being created, specify a display profile (e.g. sRGB) as the source gamut. If a display profile is being created, then specify a printer profile as the source (e.g. Figra, SWOP etc.).  When linking to the profile you have created this way as the output profile, then use perceptual intent if the source is the opposite type, and relative colorimetric if it is the same type."

I had seen a lot of other folks documenting this process were using aRGB instead of sRGB.   My original question might actually not be relevant or useful.    I might experiment with a number of differnet profiels there to see what happens.

I've use PP before, and wasn't always happy with the results or the workflow.   I update every once in a while.  I do love the profile editor.  I wish Mike would make it usable on profiles created by other tools.

Thank you for all of your answers.

Bob

Well, not the most well written piece but this is how I interpret it, reading between the lines...

The ICC color management model only allows colors to be converted from one profile to another by a hard coded mapping (a matrix or a look up table).  If the color space of your image (say Adobe RGB) is larger than that of the device you are using (say a printer), some of the colors in the color space of the image may be out of gamut for the printer.  Perceptual and Saturation intents attempt to do some scaling so that the larger image gamut can be displayed on the smaller gamut of the device without clipping.  This is done by "squeezing" the larger gamut into the smaller one, basically by desaturating the colors just a bit since the ones that are out of gamut will be the brighter colors.

They are trying to compensate for ICC profiles not being "smart" by rescaling gamuts differently depending on the color space you use for your images.  If you are creating a printer profile and you say your color space is Adobe RGB, they squeeze the gamut a little so (most or all) of Adobe RGB can be printed on your printer without banding or hot areas.  This results in a little desaturation of the colors because you can't truly display all of Adobe RGB on your printer: but you can desaturate so it at least looks smooth.  By comparison, if you say your image color space is ProPhoto RGB, they squeeze the gamut a lot because that color space is much larger, resulting in even more desaturation of colors.

IMO, this is not a good idea!  First of all, a "smart" CMM would be able to look at the actual colors present in the image, and only scale to fit those instead of the entire color space.  Just because you use ProPhoto color space doesn't mean that all your pictures are going fill that entire color space and be of incredibly saturated flowers that are out of gamut for the printer.  What if you print a picture of your brother's new black car with just some grass and blue sky in the background: all of which are well within the color gamut of your printer: do you want the green grass and blue sky rescaled and dulled just because you use a big color space?  The second problem here is one of impracticality.  You create a printer profile based on ProPhoto input color space and now you want to print a photo from a friend's iPhone, or an sRGB JPEG from a friend's camera.  Now you have to use a different profile if you don't want that sRGB image to suffer the "ProPhoto squeeze".

Rather than trying to scale gamut for Perceptual and Saturation intent based on the potential size of the entire color space (only a fraction of which may be visible in your images), it is better to take a "real world" approach where the gamut of the device is examined and that is compared to a set of colors that is expected in nature and man made objects that typically appear in the majority of photos.  Then one profile works regardless of the color space of the images.  The majority of your photos won't go beyond even the small sRGB color space so why "penalize" them by desaturating them so that all possible colors in ProPhoto (for example) are able to be "shaded" by your printer?

By comparison, Profile Prism uses a proprietary scaling of the color gamut based on known properties of colors that are typically photographed compared to the (measured) gamut of your printer.  It is also non-linear so that your light blue shirt isn't penalized for being in a color space big enough to capture all of nature.  

BTW, none of this applies if you use Relative Colorimetric intent.  That intent renders all colors in gamut accurately, and simply clips the ones that are out of gamut.  Also, I use ProPhoto here as an example only because it is the largest of the generally used color spaces and makes my point of the level of scaling being done from one space to another.

HTH,
Mike

Hi Mike,

Thank you for wading through all that techno babble for the rest of use and giving a decent concise answer.  I haven't used PP for over a year, but not that I think about it, I hadn't created an Argyllcms profile in over a year.  I typically try both.   The think I like about PP is the opportunity to refine the profile.   In the end though, I use my profiles from my Pulse DTP20 and Argyllcms because I'm happier with my test prints with it.

For anyone who doesn't want to invest hundred of dollars for dedicated profiling equipment and want to take a stab at profiling their printers (scanners, and cameras also), Profile Prism does an amazing job if you have the right printer, and software that will do a raw scan of the it8 target and the printed target.   

I don't know if I will pay for PP support this year.  Maybe after the next upgrade.   Also, I don't have the software to read the raw images or my canon lide scanner any more.

Many thanks to everyone for responding to my question.  I'm always learning from you guys.

Time to make some prints with Qimage Ultimate!

Bob Coss

Yes.  Each image is converted from the image's color space directly to the printer color space and the images are resampled and sent to the driver individually (each in chunks).  It doesn't try to render multiple images at once.  If it did that, you wouldn't be able to print (properly) images that have different color spaces.

Regards,
Mike