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Custom-shaped histogram

version 1.1 (1.65 MB) by

Transform an image to have any histogram you want.

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This script transforms an image such that the object in the "foreground" of the image now becomes the histogram of the transformed image.
I provide three examples with 3 demo images:
   I change the image of a city skyline so that the histogram of the new image looks like the skyline.
   I change the image of a car so that the histogram of the new image looks like the car shape.
   I change the image of a woman so that the histogram of the new image looks like the shape of the woman. (See screenshot)
The script can also produce a perfectly flat histogram - the ultimate histogram equalization, far better than any standard histogram equalization method because the final histogram is TRULY FLAT.

In addition I give some examples for how to segment multi-colored objects (car, skyline, woman) out of the foreground of the image, thus demonstrating some standard image processing techniques such as color classification and thresholding.

As an extra bonus, I provide a thresholding GUI application where you can interactively threshold your image with scrollbars and see the results (original, binary, and masked) immediately. You can use this with any integer or floating point image. Here, if you uncomment it in the code, you can use it to select threshold values for the hue, saturation, and value channels of the "beach_woman" image. But it can be used in general for any image - it's not specific for this shaped histogram script, it's just bundled in.

Comments and Ratings (13)

junnie vix

any idea how to extract shape?


Mandip (view profile)

Ellie Dadkho

Ellie Dadkho

it is fantastic code idea. just want to say thanks. Its really useful for some one like me as a learner.


Fer (view profile)


M W (view profile)

Image Analyst

Image Analyst (view profile)

yang: You can't call the threshold function by itself with no arguments - you have to pass it an image array that you want to threshold. I'll see if I can put in a warning when someone tries to use it (like you did) without passing in the required arguments.

yang ??

can't run the file:threshhold.m
??? Error using ==> deal at 38
The number of outputs should match the number of inputs.

Error in ==> threshold>threshold_OpeningFcn at 95
[g_MinThreshold, g_MaxThreshold, ImageFilename] = deal(varargin{:}); % copies the contents of the cell array X to the separate variables
        Y1, Y2, Y3, ...

Error in ==> gui_mainfcn at 221
    feval(gui_State.gui_OpeningFcn, gui_hFigure, [], guidata(gui_hFigure), varargin{:});

Error in ==> threshold at 61
    gui_mainfcn(gui_State, varargin{:});

Image Analyst

Image Analyst (view profile)

Pasco. Sorry - the file should now be included. Please try again. Thanks. Also made a few other updates.

Pasco Alquim

The function threshold_grayscale_image is missing



Made bar chart have the same aspect ratio as binary image. Included missing threshold m-file.

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