resize or scale image file size is too big

[glennrp]

If the original doesn't have very many colors the resized one will have more. Use "identify -verbose" to find out how many colors are in your original, your output jpeg, and your output png. That may provide an explanation for the size differences.

[glennrp]

Hi, Just ran identify on all the three images and this is the output. Any ideas? When output is jpg, it is defnitely not black and white image even if the source is. Looks like convert to png is fine. What could be causing this?

Your results are OK. It's just that JPEG doesn't support pure black/white. The sharp edges get smoothed out with additional levels of gray.

Glenn