error in using imhist in matlab 2015a. i cant understnad why error is coming

Answer 1

[Image Analyst]

Probably because it's color. Use histogram() or else use imhist() on each color channel one at a time.

% Extract the individual red, green, and blue color channels.
redChannel = im(:, :, 1);
greenChannel = im(:, :, 2);
blueChannel = im(:, :, 3);
[countR, grayLevelsR] = imhist(redChannel);
[countG, grayLevelsG] = imhist(greenChannel);
[countB, grayLevelsB] = imhist(blueChannel);

Or convert to gray scale:

grayImage = rgb2gray(im);
[countR, grayLevelsR] = imhist(grayImage);