Mike Chaney's Tech Corner

Hello Mike,

I am preprocessing my Nikon  pictures ( under adobe RGB within the camera) using  using now permanently the Prophoto RGB color space within the derawtizer Nikon Capture Nx2 . Then i generate tiffs to enter in QI.

Please can you tell most of us,  if there is any inconveneince for QI to leave ProhotoRGB as color space before entering QI or do we have  to  convert explicitely in adobe Rgb or any better color space before genating tiffs for QI ingestion.


MAny thanks in advance

C Torres

Toulouse France

Hi

QImage will print files in Prophoto, but because the gamut of Prophoto is much larger than the printer gamut there may be unexpected colour differences due to the rendering intent used .
There is no real advantage in using Prophoto at any stage for normal use, as the gamut of the aRGB colour space from the camera will be approximately to same as the gamut of the printer. You will not get any change in colours when you convert to Prophoto - if you pour a litre of beer into a 10 litre glass you still have a litre of beer - and any changes you make outside the aRGB gamut will not be printed and you definitely will not see them on your monitor.

Brian

Thanks Brian,

Effectively i made a test which confirm that QI keep prophoto and doesnt convert to other system : when the picture is in Prophoto, all colors and tones around the mid values are kept  but the contrast and saturation are smooth and of low saturation. I didnt tested with extreme colors, but you are right.

But, ok that a litre ( of wine for me) within a glass of 10 remains 1 litre. But when doing a cascade of sophisticated processings you keep a bit more smoothness in a wider space than on a limited space or in any case errors remains lower for smooth transition. Then when converting to argb i imagine i have a chance to keep my smoothest transitions  if not they are gone before entering into QI.

Just for info Adobe  lightroom is now internally working in prophoto and no longer in arvb even if most of their customers are working in srgb and arvb.

Claude

This is correct but you can setup the edit in preference in Lightroom to send a tiff or jpeg to Qimage  for printing in ProPhoto, aRGB or sRGB

Ok thanks .

So it means that pictures need to be converted in other system because QI doesnt know or manage Prophoto.
I will test both.

No!
Qimage is fully colour management aware and will recognise and use an image profile when it is embedded in the image - the correct way of doing it.

If it is not embedded Q will default to sRGB (depending on your settings in the CM preferences) but you can set the image profile in those preferences based on the exif data (camera model). Alternatively you can use a profile override filter in the Editor.

Terry

Not So.

Qimage will read and honor embedded profiles.
See snaps

Fred

I think what the op is concerned with, is that qimage (at least studio) does not handle images with 32bit per colour channel, which is what many folk use prophoto for - to get smooth tone transitions if you are pushing the colours around. Within adobe photoshop, you can set prophotorgb to 8, 16, 32 bits per channel, and view and edit in any of those modes. Now when set to 16 ( or 8 ) bits per channel, qi handles the image OK, but I am not sure if in fact if qi 'translates' 16 to 8bit for editing, as it does for printing.

Best wishes,

Ray

edited - 8 +adjacent ) = 8)

I recently discovered my TIFF files out of Photoshop CS5 are 48 bit.  I've been playing with ProPhoto lately and something is messed up.  Some, depending on some CS5 Actions I've used, will drop from 48 bit to 24 bit when I look at their internal data.

If I go right from the camera via JPG or NEF (Nikon) images look fine in QI 2012 and print the same using the profiles I have for the papers I made using Prism 7.

If I go through Photoshop and do some PP work and save as a TIFF, the thumbnails in QI look reddish are dark.  Prints aren't much better.

Something is screwy in my PS CS5 somewhere or some other profiles are crossing over someplace.  I have Paint Shop Pro X3 as well as DataColor Spyder so something is messing up the TIF's in CS5 and QI is not liking it.  I know from CS5 (64 bit) to PSP X3 issues can result in screen color and output.  PSP X3 is back in 8 bit era or somewhere.

Don't know why it looks great in CS5 and I save to TIFF and QI2012 will see it as red and dark in the thumbnails?  BMP out of CS5 to QI2012 are a bit better, but still off.   ???


Mack

Hi Mack,

Generally, if you have an adobe rgb profile assigned to a cs5 image, it looks fine on the screen with cs5, however, if you save the image without converting it, then when viewed outside of cs5 an srgb space may be used, giving a reddish tinge to the image. 

I expect you are not converting the colour spaces correctly within cs5. Many of the cs5 functions only work on 8 bit per channel images.

hth,

Best wishes,

Ray