Contrast stretching diagram formula with imadjust function in matlab

Help me.... I have an image output contrast stretching use function "imadjust"

How i can see a diagram like bellow with my image contrast stretching...?

Answer 1

[KALYAN ACHARJYA]

1. Suppose you have input image, say input_image
2. Do the some gray lebel operation, say the result is output_image;

Here when apply the transfer function, pixel values will be changed, right,

Say Pixel Values in input image                          After transfer function Pixel Values in output image
0                                                                           2
1                                                                           5
.................................
255                                                                        255  

Now plot the cloumn1 vs cloumn 2 in above example. The plot in nothing about the image, its how you replace the invividual pixel value using some maths equation right (Transfer Function)

Let see the an example, transfer function is log(r), r represent the pixel values in input image

input_pixels=0:255;
output_pixels=log(input_pixels)
%% Plot
plot(input_pixels,output_pixels);
xlabel('Input Intensity Levels');
ylabel('Output Intensity Levels');
xlim([0,255])

In the plot, you have shown of contrast stretching having three relations between input vs output

First Segment-

Second Segment-

Third Segment-

Hope it helps!, Any questions are welcome

[Nayuta Altria]

Hmm.. Actualy i want get diagram in contrast stretching formula with output images use function "imadjust"...

[KALYAN ACHARJYA]

input_im=rgb2gray(imread('2.png'));
input_pix_value=unique(input_im(:));
output_pix_value=10+imadjust(input_pix_value,[0.3 0.7],[]);
plot(input_pix_value,output_pix_value,'linewidth',3);
xlabel('Input Intensity Levels');
ylabel('Output Intensity Levels');
xlim([0,255]),ylim([0,255]);

Dp change the transformation function and get the required shape, I added the extra 10 in each pixels

Answer 2

[Ali Abdullah]

[Ali Abdullah]

Contrast stretching