Task: Write a script to read the image in Image3.png. Determine the range of color numbers for this image. Create a new image with color numbers spanning half of the range of the original image. Display both images.
Because image descriptions are contained in arrays of integers, it is relatively easy to manipulate the image. A png image is an indexed image where each pixel has a single integer indicating the color number. You can manipulate the colormap to change the colors. Or you can manipulate the color numbers for a larger effect.
Consider that the image has color numbers from 1 to 64 (like the .png image above). Then it is possible to shift the color numbers. Consider the following transformations:
IM2=imread('Image3.png');
IM2a=IM2;
i=find(IM2 > 32); IM2a(i)=64;
i=find(IM2 < 32); IM2a(i)=1;
figure
image(IM2a);title('Modified image 3')
%
IM3=.5*(IM2-32) + 32;
figure
image(IM3)
The first example shifts all colors above 32 to be the top color (64) while all colors below 32 will be the first color (1). The middle color (32) remains in the image. The second part reduces the color range to be half of its original range relative to the middle color.
The script below takes the flujet image (400x300) and averages the colors over 30x30 pixel blocks, creating a blocky looking image.
FJ=load(flujet.mat);
im4=FJ.X;Bim4=im4;
for i=1:10
ia=(1+(i-1)*30):(i*30);
for j=1:10
ja=(1+(j-1)*30):(j*30);
m=mean(mean(im4(ia,ja)));
Bim4(ia,ja)=m;
end
end
figure;image(Bim4);colormap(FJ.map);title('Blocky flujet')
Similar commands can be used with true color (RGB) images.
Flow chart to accomplish task:
%%% read image file %%% display image %%% determine min and max color numbers %%% determine middle color number %%% create new image with different color numbers %%% display new image
Script to accomplish task:
FILE3='Image3.png';
%%% read image file
im3=imread(FILE3);
%%% display image
figure;image(im3);title('Original Image3')
%%% determine min and max color numbers
minC=min(min(im3));maxC=max(max(im3));
%%% determine middle color number
midC=round(.5*(minC+maxC));
%%% create new image with different color numbers
Mim3=round(.5*(im3-midC));
%%% display new image
figure; image(Mim3);title('Modified Image3')
