how to find the pixel that drop from 0-100

Here it is my code:

global a;
a=imread('.jpg')
a_gray=rgb2gray(a)
subplot(1,2,1)
imshow(a_gray)
subplot(1,2,2)
imhist(a_gray)
intensityValue(0,100)

Answer 1

[KSSV]

idx = a >= 0 & a <=100 ;
iwant = nnz(idx(:)) ; 

Answer 2

[Ashwin]

My understanding is that you require a way to identify the total number of pixels that have an intensity value between 0 and 100.

The a_gray array that you used to convert the image from RGB to grayscale contains the intensity values for the pixels as well. To find out the number of pixels, we can do:

val = sum(a_gray>0 & a_gray<100,'all'); 

Where ‘all’ parameter helps calculate in this case the number of 1s across all dimensions of the array,

Conditions a_gray>0 & a_gray<100 compare each element of the array to see if they match the condition.