how to create a black image?

how can i create a black image, not a gray one?

[Jia Yu]

thanks for reminding!

Answer 1

[Cris LaPierre]

Can you use imshow?

If you have to use imagesc, keep in mind that an image has to have values for R, G and B for each pixel. That means you matrix needs to be 256x64x3.

Try using imagesc with this

img=zeros(256,64,3,'uint8');

[Jia Yu]

thank you so much!

[Image Analyst]

You can also create a gray scale image, rather than an RGB color image if you do

img = zeros(256, 64, 'uint8');

Also note that imagesc() does not require a color image. You can pass it a grayscale image. However it, for some weird reason, pseudocolors it. To turn off the colormap, you can apply a colormap of all grays:

grayImage = imread('cameraman.tif'); % Read in a gray scale image.
imagesc(grayImage); % Display it with a funky colormap
colormap(gray(256)); % Turn the colormap off by making it normal gray.

[Jia Yu]

thanks!