Colour Management on PTE5

[JohnB]

The colour management forum stream ran out a few months ago, but I'd like to start a new one by asking Igor to incorporate proper colour management in PTE5. As far as my very limited tests show, PTE5 will need very good graphics cards to run smoothly and I think Igor said somewhere that he would need good graphics cards to incorporate proper colour management.

So this is your chance, Igor! Give us proper colour management with PTE5!!

Digital imaging competitions are becoming common nowadays, and, in Kent at least, several clubs already have GretagMacbeth Beamers to profile their projectors (thanks to Lottery grants), so now we should bite the bullet and show images with their correct colours.

By the way, I looked through the old forum stream before writing this and noticed that some people said you can't see the difference between sRGB and Adobe RGB 1998 -- WRONG.

Try this simple test: load a colour image with a reasonable range of colours into Photoshop and duplicate it; set one image to be in sRGB and the other in Adobe RGB 1998 and resize them so you can see them side by side. You can do this either on your computer monitor or on a projector screen. I haven't found anyone who can't tell the difference when they can see the two images together. That includes me and I'm partially colour blind!

[ronwil]

So which gave the correct colours, sRGB or Adobe RGB 1998? And who says which colours are correct, you, me or Joe Bloggs?

The portrait used in my avatar was taken by a former President of the Royal Photographic Society. Are the colours correct?

Ron [uK]

[Igor]

John,

It's not simple question.

Probably my knowledge wrong, but because almost all output devices (displays, projectors) have sRGB format it is enough to have global color profile installed in Windows for particular display.

Also Direct3D (and even modern videocards) which we use in the new graphical engine doesn't support color management for individual images. And it better to use Photoshop to convert each image to sRGB format.

[JohnB]

So which gave the correct colours, sRGB or Adobe RGB 1998? And who says which colours are correct, you, me or Joe Bloggs?

The portrait used in my avatar was taken by a former President of the Royal Photographic Society. Are the colours correct?

Ron [uK]

The 'correct' colour is not at all easy to define – do you mean that the colour on the screen is the same as that of the original object when that object is illuminated by the same intensity and colour temperature light as that used when taking the photograph? If that's your criterion, then if the camera was correctly profiled to use Adobe RGB 1998, then the Adobe RGB 1998 image is correct, provided the viewing device is correctly profiled. If the camera is correctly profiled for sRGB, then the sRGB image will be correct.

Anyway, I didn't say that one or the other is correct, I said that they were perceptibly different.

About your portrait, do you know whether the President of RPS used a digital or film camera? If the latter which film did he use? Did he allow for the colour characteristics of that film? And so on, and so on.

[nickunwin]

John,

Igor doesn't need to be concerned with handling colour profiles in PTE - the colour profile is independant of PTE and is handled by LUT's within the video card manufacturer's drivers. If you have profiled the graphics card/output pairing, then the system will be colour profiled.

FWIW, Very few monitors are capable of displaying anything other than the sRGB colour space, and a lot of them don't actually manage that all that well! Only a few high-end monitors can begin to approach the aRGB colour space - and those cost several thousand $/£'s .

[JohnB]

John,

It's not simple question.

Probably my knowledge wrong, but because almost all output devices (displays, projectors) have sRGB format it is enough to have global color profile installed in Windows for particular display.

Also Direct3D (and even modern videocards) which we use in the new graphical engine doesn't support color management for individual images. And it better to use Photoshop to convert each image to sRGB format.

I agree that most output devices have the sRGB gamut, but some don't. A good quality projector when profiled using the GretagMacbeth beamer can approach the Adobe RGB 1998 gamut, according to GretagMacbeth. And there are (very expensive) monitors which can even exceed the Adobe RGB 1998 gamut.

However, the ultimate gamut of the viewing device isn't the whole story, what we need to do is handle profiled images correctly. For a competition, it isn't really ethical for the organiser to change a submitted image in Photoshop using a perceptual, or relative colorimetric, or absolute colorimetric conversion (-- WHICH?) to suit his/her own set-up.

If someone is making a PTE sequence for him/herself, everything is under control and choices can be made without having to consider other people. But if we want to create a file so that a succession of images from many different (say, 100) people can be viewed so that every image is given the best chance, we need proper colour management.

Sorry to be so dogmatic, but I've been involved in the problems of what to do with images having different profiles, and when it is frequently impossible to contact the originators for their opinions on how to proceed.

[JohnB]

John,

Igor doesn't need to be concerned with handling colour profiles in PTE - the colour profile is independant of PTE and is handled by LUT's within the video card manufacturer's drivers. If you have profiled the graphics card/output pairing, then the system will be colour profiled.

FWIW, Very few monitors are capable of displaying anything other than the sRGB colour space, and a lot of them don't actually manage that all that well! Only a few high-end monitors can begin to approach the aRGB colour space - and those cost several thousand $/£'s .

I'm afraid your first paragraph isn't the whole truth. You're considering only the output side of the digital imaging process; the input side has to be included as well. That means the profile attached to the image (by the camera if it's a good one) has to be 'carried forward' across the computer onto the output side. So the overall colour profile of the whole system (if I may invent a convenient concept) is NOT independent of what PTE might do to the image.

See my reply to Igor about monitors etc. Basically I agree with you, but I submit that the capabilities of the output device aren't the whole story.

[Igor]

John,

Anyway unfortunately Microsoft didn't provide support of color profiles in DirectX at all. No modern or future video cards support it. I didn't hear about this feature in the next version of DirectX 10.

I appreciate your wish for exactness of color and care about them, I also spent much time for fine calibration of my projector.

[nickles]

Hello:

I am far from being an expert in color profiles or gamuts. I know at one time I attempted to correct all my devices to adhere to Adobe RGB 1998...including monitors, video overlay, scanners, printers and digital camera raw. I never seemed to get satisfactory results...probablly because I didn't know what I was doing. But I feel that I get very consistant results when I adhered to srgb. The worst thing that came of my Adobe RGB experience was that my customers monitors displayed my images totally different than what I was seeing. By sticking with srgb...what my customers see seems to be much the same as I see. This is more important to me as the images are primarily created for them to enjoy more so than for myself.

I'm also one who believes that what the image conveys is many, many times more important than the precise technicalities of color, contrast, sharpness, saturation, etc.

Just my unprofessional personal thoughts,

Sincerely

Ken

[nickunwin]

Hello John,

Agreed, they do need to take into account the working space of the output device - but it is the competition organiser who should stipulate the requirements Eg entries should be submitted as sRGB files. Would you have expected a slide competition which was going to project the slides to cater for all sizes of slide? What about the guy using his home brew with big glass plates? Or would the judges have sensibly set a few guidelines such as 35mm or suchlike?

While it would be very nice, it is a bit unfair to ask Igor to have to build in a complex colour profile conversion engine to work in realtime and at high res & refresh rates.

[JohnB]

Hello John,

Agreed, they do need to take into account the working space of the output device - but it is the competition organiser who should stipulate the requirements Eg entries should be submitted as sRGB files. Would you have expected a slide competition which was going to project the slides to cater for all sizes of slide? What about the guy using his home brew with big glass plates? Or would the judges have sensibly set a few guidelines such as 35mm or suchlike?

While it would be very nice, it is a bit unfair to ask Igor to have to build in a complex colour profile conversion engine to work in realtime and at high res & refresh rates.

A quick reply: in an ideal world entrants would indeed submit their images in the specified colour space, but they don't! Last time, we had sRGB, Adobe RGB 1998 (the one we asked for), CMYK, Greyscales with different gammas, as well as several unidentifiable ones which looked very peculiar.

In the analogue world things are a bit better: we usually find nowadays that slide mounts are 5 by 5 cm but until a couple of years ago we used to get a few medium format slides as well! And don't to talk to me about print mount sizes! The only way we forced people to use the size asked for was to completely reject all those that were wrong one year -- this caused a real stink, but seems to have done the trick.

[Ken Cox]

John

maybe you should modify this quote to suit your rules and include it on the entry form.

ken

quote from PCWorld

* Hot Pic of the Week *

Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique. Every month, the best of the weekly winners gets a prize valued at between $10 and $100.

A gentle reminder, folks: We disqualify some really wonderful pictures every week because the submissions don't follow the rules. Be sure to include everything we ask for in your e-mail message, including a description of your picture and your complete contact information, or your entry is wasted!

Here's how to enter: Send us your photograph in JPEG format at a resolution no higher than 640 by 480 pixels. Our e-mail address is:

hotpic@pcworld.com

Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering, please read the full description of the contest rules and regs at:

http://www.pcworld.com/resource/article/0,...l_dfxrsc,00.asp

[nickunwin]

A quick reply: in an ideal world entrants would indeed submit their images in the specified colour space, but they don't! Last time, we had sRGB, Adobe RGB 1998 (the one we asked for), CMYK, Greyscales with different gammas, as well as several unidentifiable ones which looked very peculiar.

....

The only way we forced people to use the size asked for was to completely reject all those that were wrong one year -- this caused a real stink, but seems to have done the trick.

I think you've given an answer to the issue yourself in your last sentence. Should we really be asking Igor to spend a lot of programming time simply because a few people can't follow rules/guidelines/best practice?

Look at it this way - it's one way to cut the entries and make the judges lives easier - that way they might even get to the pub quicker.

Sort the cause of the problem (your entrants) and don't stick a plaster over it (Igor/PTE+Colour Engine)

[JohnB]

John

maybe you should modify this quote to suit your rules and include it on the entry form.

ken

quote from PCWorld

* Hot Pic of the Week *

Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique. Every month, the best of the weekly winners gets a prize valued at between $10 and $100.

A gentle reminder, folks: We disqualify some really wonderful pictures every week because the submissions don't follow the rules. Be sure to include everything we ask for in your e-mail message, including a description of your picture and your complete contact information, or your entry is wasted!

Here's how to enter: Send us your photograph in JPEG format at a resolution no higher than 640 by 480 pixels. Our e-mail address is:

hotpic@pcworld.com

Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering, please read the full description of the contest rules and regs at:

http://www.pcworld.com/resource/article/0,...l_dfxrsc,00.asp

I note they don't specify the particular colour space -- that must explain why so many pictures in magazines look very strange! But is colour managing so very difficult? The slide viewing programs Thumbs+ and Irfanview, to name but two, have colour management built in.

[nickunwin]

.. But is colour managing so very difficult? The slide viewing programs Thumbs+ and Irfanview, to name but two, have colour management built in.

No, it's not so difficult - but the big difference is that they don't have to do it while moving the shots around the screen simultaneously. From what I understand, colour conversions need to undergo at least two transformations - from the original to an "neutral" intermediate, and then from the intermediate to the target colour space.

Try doing that on the fly, with very large photos flying around your screen whilst fading out. Then add in another shot zooming in and fading in too, and a few other bits such as text (still a colour image at the moment - eg PNG) whizzing around and you begin to see the headache that Igor would have .

It seems a few PC's are already having problems feeding the images into the video card memory..think how much slower it would get if he also had to contend with colour management .

I once accidentally turned on the in-built colour management in the DVD player on my laptop (Not the colour profile done by a colorimiter like the Optix or Spyder). It took me ages to work out why all the movies had suddenly begun to play back jerkily - and they're only small "pictures" running at 24/25 fps. If I turn colour management on in Breezebrowser or CaptureOne, then things slow down, even on an x2 dual processor system - but I can live with it because I'm only looking at one shot and taking my time.

Make life easier ..ask for and stick to sRGB (or one colour space!)