How to draw a graph of an image with frequency in y axis and pixel value in x axis in matlab?

How to draw a graph of an image with frequency in y axis and pixel value in x axis in matlab?

[Joy Tian]

Is histogram ok?

[Anushka]

Sir I want the graph as shown below

[Anushka]

Share and secret are two images

Answer 1

[Image Analyst]

% Extract the individual red, green, and blue color channels.
redChannel = secret(:, :, 1);
greenChannel = secret(:, :, 2);
blueChannel = secret(:, :, 3);
[pixelCountsR, grayLevelsR] = imhist(redChannel);
[pixelCountsG, grayLevelsG] = imhist(greenChannel);
[pixelCountsB, grayLevelsB] = imhist(blueChannel);
plot(grayLevelsR, pixelCountsR, 'r-', 'LineWidth', 2);
hold on;
plot(grayLevelsG, pixelCountsG, 'r-', 'LineWidth', 2);
plot(grayLevelsB, pixelCountsB, 'r-', 'LineWidth', 2);
grid on;
fontSize = 20;
ylabel('Frequency', 'FontSize', fontSize);
xlabel('Pixel Value', 'FontSize', fontSize);

Then just do the same for share. Then you can use text() and annotation() to add text labels and arrows wherever you want them. Or you can use legend().

[Anushka]

Thank you Sir.Sir how to divide y axis as shown in above figure,i.e as 0.000,0.002 and so on..

[Anushka]

Hi,Image Analyst

Can you please tell me a way to divide the y axis as shown in the figure ie,0.000,0.002 and so on.

[Image Analyst]

Anushka:

Try this:

x = 0:255;
y = 0.0018 * rand(1, length(x));
plot(x, y, 'b-');
ax = gca;
ax.XTick = 0:50:250;
yTicks = 0:.0002:.0018;
ax.YTick = yTicks;
for k = 1 : length(yTicks)
  YTickLabels{k} = sprintf('%.4f', yTicks(k));
end
ax.YTickLabels = YTickLabels;

Answer 2

[Guillaume]

doc imhist

[Anushka]

Sir I want the graph like shown below