Is the number of histogram pixels the same for each channel within each layer?

Question

Dear Photoshop Scripting Forum:
I have written a script to isolate the number histogram pixels for each channel within each layer of a file.
However, I have found some unexpected results: That, the number of pixels is the same for each channel within each layer.
For example,
  Layer 1 has 18,979 pixels by itself, and so does each channel within it (Red, Green, and Blue)
  Layer 1, Channel Red, has 18,979 pixels
  Layer 1, Channel Green, has 18,979 pixels
  Layer 1, Channel Blue, has 18,979 pixels.
This does not seem right to me.
Does someone else have the same experience, or knowledge of something else?
I am wondering if there is a bug in my script.
If need be, I will post the script, but it's kind of long for a forum.
Thank you.

Answer 1

The following is for RGB 8bit images.
The red historgram is an array of red values of the pixels that range from 0 to 255. Each element in the array has the number of pixels that have that red value. So for example if you had a layer that is pure red 255,0,0 all the pixels would be in the 255 element and there would be no pixels in the other elements. The red historgam still has the same number of pixels as the layer. They are just all in one histogram element( they all have the same value ).
But even if you know that all the pixels in a layer are all in the last element(255) of the red histogram you still don't know the color of the pixels. A white pixel has a red value of 255. So does a yellow, magenta, etc pixel. If you only know the red value of a pixel the pixel could be one of over 65000 colors. Most of which would not be considerd 'red'
It is the three channels together that detemine a pixel's color. Unless the layer is one color you can not tell the color of the pixels from looking at the histogram.
Unless you use the color range selection then get the histogram of the selection. Even then you need to decide what color value make up 'red'