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color area

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Ath:
In case of the skinchart picture, a selection like using the lasso tool of lots of graphics editors would be the easiest way of handling that process. Then counting the pixels inside would give a percentage covered by it.
But what would that need to be compared to? Total no. of square mm, but how to relate that to the pixelcount? (like Renegade already said) You would need a confirmed measuring standard on the same photo to be able to compare, like the crime-scene photo's you see in TV series like CSI.

Deozaan:
Isn't this what the Magic Wand does in just about every paint/photo program out there?

Renegade:
If someone knows how to do it in Photoshop, chime in. I don't know of how the Magic Wand helps...

Here's an ASCII representation that is impractical for the Magic Wand (to count the "O"s):

---O---O---O---O---O---O---
-O---O---O---O---O---O---O-
---O---O---O---O---O---O---
-O---O---O---O---O---O---O-
---O---O---O---O---O---O---

Or with X's just to make it more painful to look at:

XXXOXXXOXXXOXXXOXXXOXXXOXXX
XOXXXOXXXOXXXOXXXOXXXOXXXOX
XXXOXXXOXXXOXXXOXXXOXXXOXXX
XOXXXOXXXOXXXOXXXOXXXOXXXOX
XXXOXXXOXXXOXXXOXXXOXXXOXXX

That's the first problem for the Magic Wand - You must manually select all similar colour patches yourself, which defeats the purpose of doing it manually.

Next, I don't know how to get a pixel count from the Magic Wand. Anyone know how to do that?

Deozaan:
Hmm... That's right. It doesn't select all similar colors. Only connected ones.

I don't use Photoshop, but I remember in PSP several years ago you there was either an option to make the Magic Wand select all similar colors in the entire image, or you could select a color and then use a menu option to select all similar colors. Something like that. . .

Once you've got all the pixels selected there is still a bit of a problem counting them. One way to do it could be to make the selection one color and make everything not selected a different color so you've got just a two-tone image and then use coding magic to figure it out from there. That's based on the assumption that it's easier to count specific pixels in a two-tone image than a 32-bit color image.

If it sounds like I don't know what I'm talking about, that's because I don't. I'll shut up now. :-[

tomos:
That's the first problem for the Magic Wand - You must manually select all similar colour patches yourself, which defeats the purpose of doing it manually.
-Renegade (February 12, 2012, 11:20 PM)
--- End quote ---

again, in my ancient version of photoshop:
Contigious selected = select adjacent pixels of same colour (or similar colour - depending on the "tolerance")
Contigious deselected= select pixels of same colour (etc.) throughout the image

No idea how to count them though...
and,
as per Ath's post above, I dont really understand the request in the context of the example given...

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