Here is a strange problem,please help

[sunng1]

what I'm doing:
1.get one frame from a gif picture(we call it Frame f) using CloneImage function;
2.change some pixels of Frame f;
3.save the Frame f;

then, my problem is :

If I save the Frame f as jpg, everything is OK,
but if I save the Frame f as gif, my changes(done in step 2) does not work, the output gif is the same as the orginal Frame(got in step 1)

and I want to get a gif format output, how should I do?

[magick]

Your original image is PseudoClass (colormapped). You have the choice of either changing the color of one or more colormap entries or if you want to change a single pixel, first promote the image to DirectClass (e.g. SetImageStorageClass()).

[sunng1]

thank you so so much!
it does work!

Your original image is PseudoClass (colormapped). You have the choice of either changing the color of one or more colormap entries or if you want to change a single pixel, first promote the image to DirectClass (e.g. SetImageStorageClass()).