ICC on color picker
JonCruz,
I've been looking at the dropper-context.cpp code. It deals with sRGB colors only. I think that we should be able to pick an ICC color using the color picker. But there are some issues here:
1) the color picker acquires the rendered sRGB image of the document (a NRPixBlock) and colects the color of a single pixel (or an average). These pixels can be the result of compositing various layers of semi-transparent objects. We will need to implement icc-color compositing on our own if we wish to pick an equivalent color in the transformed color space.
2) Colors can be altered by filters, which are calculated in sRGB. So, it wouldnt be possible to pick an equivalent ICC color even when we are trying to pick a color from a filtered object that has an icc color in its fill or stroke.
3) how to deal with compositing of mixed color spaces? I.e. how to mix sRGB with icc transformed colors? Or even... how to mix colors in two (or more) color profiles? This seems to be hard to solve...
I'd like to know what's your (JonCruz and Inkscape devel team) opinion on that subject.
Juca
On Mon, Jun 22, 2009 at 8:48 PM, Felipe Sanches<felipe.sanches@...400...> wrote:
JonCruz,
I've been looking at the dropper-context.cpp code. It deals with sRGB colors only. I think that we should be able to pick an ICC color using the color picker. But there are some issues here:
My probably uninformed opinion is that, as these issues demonstrate, it is not a good idea to try to pick any non-RGB color at all. Inkscape rendering works in RGB, the screen works in RGB, and pretending that what we picked from the screen is not RGB is inherently clumsy. If you want to pass one object's ICC reference to another object, just use copy/paste style, color picker is a wrong tool for this.
On Jun 22, 2009, at 6:02 PM, bulia byak wrote:
On Mon, Jun 22, 2009 at 8:48 PM, Felipe Sanches<felipe.sanches@...400...> wrote:
JonCruz,
I've been looking at the dropper-context.cpp code. It deals with sRGB colors only. I think that we should be able to pick an ICC color using the color picker. But there are some issues here:
My probably uninformed opinion is that, as these issues demonstrate, it is not a good idea to try to pick any non-RGB color at all. Inkscape rendering works in RGB, the screen works in RGB, and pretending that what we picked from the screen is not RGB is inherently clumsy. If you want to pass one object's ICC reference to another object, just use copy/paste style, color picker is a wrong tool for this.
I think bulia has it halfway here. I think we will need to allow for it since many users try to use it that way. However, we'll have to do it "right". What he pointed out will have to be addressed.
One thing is that as we move more towards using style (CSS styles), we'll have to preserve that in the workflow as much as possible also. When the picker is over our own canvas, it should eventually get CSS style name (when present) which in turn references and includes icc-color() on properties.
When it grabs something else (from another app's window) we could grab it as RGB, or we could possible find a current document stye that contained the same one. The latter would be a more complex piece to get right though.
On Tue, Jun 23, 2009 at 7:30 AM, Jon A. Cruz wrote:
When it grabs something else (from another app's window) we could grab it as RGB, or we could possible find a current document stye that contained the same one. The latter would be a more complex piece to get right though.
Hmmmm. Say, I have a bitmap in AdobeRGB which has a much wider gamut and I want to pick a color that is out of gamut for sRGB. What would Inkscape do in this case?
Alexandre
On Jun 23, 2009, at 6:13 AM, Alexandre Prokoudine wrote:
On Tue, Jun 23, 2009 at 7:30 AM, Jon A. Cruz wrote:
When it grabs something else (from another app's window) we could grab it as RGB, or we could possible find a current document stye that contained the same one. The latter would be a more complex piece to get right though.
Hmmmm. Say, I have a bitmap in AdobeRGB which has a much wider gamut and I want to pick a color that is out of gamut for sRGB. What would Inkscape do in this case?
Simple. What *should* happen is
1) Inkscape has been tracking color spaces of images, and knows that the one under the cursor has an AdobeRGB profile attached. 2) It grabs the original values at that location (not the adjusted ones currently used for display) 3) It gets a nice combo of original and adjusted colors.
So if the original values are RGB and the ones adjusted for display are R'G'B', then the resulting fill would be similar to
fill: RGB icc-color(AdobeRGB, R', G', B')
(with numbers instead of "R", "G" and "B", of course)
Note that by going to the original numbers we avoid re-conversion rounding error creeping in. With 8-bit components that can become significant quickly.
participants (4)
-
Alexandre Prokoudine -
bulia byak -
Felipe Sanches -
Jon A. Cruz