Most efficient way to upsample an image using ImageMagick?

Question

I have a large set of images that vary in size and resolution and I'm using ImageMagick to upsample those of low resolution. Until now, I've been using the -resample option with -sharpen as follows: convert [input image] -resample 500 -sharpen 0x2 [output image]

The issue is that it seems rather slow. The -sample option is much faster, but the quality suffers. I'm also considering switching to GraphicsMagick for a boost in performance. What is the most efficient way to upsample these images?

Some context: I am upsampling these low resolution images to increase the accuracy of an OCR tool for text recognition. The poor quality of the image causes wildly inaccurate OCR results.

Answer 1

You probably won't get any drastic speed improvements, but here are some things you can try:

• Try different resampling filters.
• Try different (smaller) support window sizes.
• Remove the extra sharpening step and use the filter:blur setting instead.