Question

I have an RGB image in MATLAB, and I want to loop through each pixel and check if it’s skin coloured (ish) [I will probably do it in HSV space at a later point to negate the effects of lighting etc.]

Does anyone know the best way to do this? MATLAB’s weird syntax is confusing me a little!

At the moment I have:

for x = 1:size(I,1)     for y = 1:size(I,2)             %Get the value from this x,y coordinate and check the colour.     end end 

But I think that's horribly wrong.

How do you access the different parts of the matrix correctly?

Answer 1

Ed,

You do not need to loop:

>> a  = magic(5)  a =      17    24     1     8    15     23     5     7    14    16      4     6    13    20    22     10    12    19    21     3     11    18    25     2     9   >> vi = (a > 5) & (a < 10)  vi =       0     0     0     1     0      0     0     1     0     0      0     1     0     0     0      0     0     0     0     0      0     0     0     0     1 

You can see how this statement could be expanded for RGB and such. I would make a function

---

function out = isFlesh(in)

%% put flesh checking code here

---

I suspect you are going to want a range of these (isCaucasian, isAsian, etc…) The problem is going to be that there is a huge range of flesh colors, so you are going to want to check for proximity to neighbors of a similar color range.

This part of the problem is easy, but the larger problem is fraught with peril.

-Doug