Digital Light & Color

Hello,

A couple questions about the Mask Tool - Colour Range.

I was recently trying to mask an area, using the Colour Range tool, of an image that has gone through some pretty radical Composite Transform iterations, including adding an image to itself with Soft Light and Hard Light blend. As some of the areas I was trying to mask were a couple of fairly narrow columns (reeds in water), I had to zoom in quite considerably. As a result, I was looking at very enlarged pixels. Although I was able to mask quite a bit of the intended pixels, a few random pixels refused to be picked up by the cursor, regardless of how many times I tried dragging the cursor and/or contracting after dragging or by changing from HSV to the other two spaces (although some pixels were successfully masked in one space but not the others).

My questions are:

- How large is the sample size for the colour range cursor? I know some of the other tools allow a choice of 1 x 1, 3 x 3 etc. but this one appears to be a single pixel, however I can't find anything in the manual that states so. To a non-expert user, it seems logical that it would be single pixel.

- Is it likely that the pixels, that aren't being picked up by the cursor, are out of the colour gamut of the tool colour space and so aren't "recognized"? If that is not likely, is there any other explanation for this issue?

- Does PWP have an out of gamut indicator?

As an aside, I am just starting to get familiar with the Apply to: Similar Pixels "fixed" and "track" of the Mask's Paint Tool and am finding it has significant potential. If anyone does a lot of intricate masking, they should give it a try if they haven't already.

Thanks in advance,

Marv

Marv

I think it was just the joice of the wrong tool for your mask.
In my personal opinion Color Range can be used for large, quiet uniform areas, but not for kind of fine structures that tend to have a high variation in color and brightness as the reed, that most likely will have a light and a shadow side and a transition in between, just because of their nature of having an round cross section.
The track method works much better for such things and it is in genreal my most prefered methods painting a mask.
Maybe you did not know, but after you have choosen a pixel in Color Range and contracted the sliders, with holding the Shift key andmoving the cursor, you can expand the range to the values of that pixels, so maybe it is worth a try.

There is nothing like a "Gamut of a Tool", only color spaces have a gamut, a range of colors they can describe or not, if they are out of gamut.
For a image processing program a pixel is only a tripple of numbers, representing the colros red, green and blue and that can go in a range from 0 to 255 in 8 bit images resp. 0-65535 for 16 bit images, so any tool just processes thes values.
The gamut is just relevant for a output device like Monitor or Printer if that color can be displayed correctly or for a Input device like camera or scanner if a given color can be digitalisized correctly.

Marv,

A technique that I'm using a lot lately is paint the item to be masked with the mask paint tool "All pixels" . I paint so the the item is entirely painted and there is overlap on the area around the item.
Then I subtract the excess using the Flood Fill tool at various threshold settings.

May not be any help for what you are working on...

Mike.

For some images, it is helpful to expand the Color Range by manually adjusting the hue, saturation, and/or brightness sliders. This process can pick up objects outside of the targeted mask area, but it is often relatively simple to erase the unwanted portions of the mask using the paint tool with an appropriate setting for the threshold.

Dieter, Mike and Couman, thanks for taking the time to reply.

Dieter - I concur that I may have tried to use the wrong tool for the stuff I was trying to do. As noted in my initial post, I have just discovered the track method (and am finding it more and more useful). I am also aware of the shift+drag method of expanding the colour range and meant exactly that when I stated "regardless of how many times I tried dragging the cursor", however, I was not as clear as I should have been. My fault! Regarding your point about out of gamut tool, the colour range tool has a drop down box that describes itself as "Colour Space" and allows the user to choose HSV, HSL or RGB. Those were what I was referring to when asking about whether the colours I was trying to mask were perhaps out of the gamut of the chosen colour space and, hence, not recognized and not masked as a result. I also queried if PWP has an "out of gamut" indicator that could be used on an image (so the user could determine if some of the image was out of gamut for a particular colour space). I am aware that Photoshop has an out of gamut warning and there are other programs that provide that info and was just wondering if PWP had the same capability. I couldn't find any reference in the literature so suspected not.

Mike - I got the "All pixels" bit but you lost me with the Flood Fill part as I have never used that tool. I will have to give it a try. Thanks.

Couman - I have often used that exact method of expanding the colour range. However, I even tried this method with the image I noted in my initial post and, for the life of me, no matter what I tried, I couldn't mask certain pixels. That's the reason I wondered if those particular pixels were out of the colour gamut of the chosen colour space. I reasoned that, by my aggressive use of the various Composite blending modes, I may have pushed the colours too much.

Thanks again everyone.

Marv

Marv

HSV, HSL and RBG are no Color Spaces in the meaning of Color Management, and do not have something like a Gamut.
From my opinion the term "Color Space" is not the most lucky choose for this, "Color Model" would fit much better.
They are indeed Models for describing a color, a pure red for example can be described in these models as follows: 0/100/100 in HSV, 0/100/50 in HSL and 100/0/0 in RGB (all values in % of the maximum value).
This does say nothing about if these color can be shown exactly on a monitor or on a printer.
There is a gamut warning in PWP, Open the Color Management Dialog (File - Color Management), on the bottom of the dialog you find the settings to switch the Gamut Alarm on and off and to set the color in which out of gamma colors are shown.
When you activate the Softproof, then, the areas that are out of gamut are shown in the selected color.
But, to say it again, there is no relevance if you show the colors in HSL, HSV or RGB, the only relevant thing if you have out of gamut colors is the pofile you print with or convert to.
The english Wikipedia article about HSV and HSL Color models gives, to my opinion, a good explanation, and also the formulae to convert between HSL, HSV and RGB, So every possible RGB color can be transverted to a HSL or HSV model, and vice versa, so there is no color in HSV that cant exist in HSL or in RGB, they are just different representations of the same color.
http://en.wikipedia.org/wiki/HSL_and_HSV

I hope it helps a bit

Dieter,

Your latest answer actually helps a lot. I admit I was a bit confused by the use of the term "Colour Space" in the Mask Tool, in reference to HSV, HSL and RGB (I made an incorrect assumption that RGB was referring to something like Adobe 1998, so further presumed that HSV and HSL had to be colour spaces as well). I agree "Colour Model" might be better. Your explanation clarifies things. And thanks for directing me to the Gamut Warning in PWP. I had looked in the Help contents and found reference to the word Gamut but could find nothing about a warning system/tool. Good to know. Logic suggested a program as good as PWP would have such a device, I just couldn't locate it.

Thanks

Marv