Options can be improved

[qgustavor]

There are some issues in the part of the code which handles resizing:

• options.height is ignored when options.width is set;
• and images smaller than options.height and/or options.height can be either upscaled or not compressed (because the comparison in line 107);

Note that, because the comparison in line 107, seems resizing is only a method to try to make a image smaller, not a requirement. I think there should be at least a note in readme about that.

In lines 94 and 96 the format of the resulting image is the same format of the original image. So the format is a choice of the end user (it can be even a BMP image). Would be better if it was an option.

Finally, is complicated to add a size limit option? Too large files can be compressed into a lossy format (like imgur, which converts PNGs larger than 5MB to JPEG).

[fengyuanchen]

Good issues and suggestion! We will improve them soon. Thanks.