How to Edit Image Size in HTML on Tumblr. If your blog images are too large, users may have to scroll to see them. Make the images too small, and blog visitors might not notice them.

The image size can be changed using simple methods. We show you the best ways and tools for lossless compression.

Density, typically in ppi, is how resolution is mapped to scale on a display or when printing. In this image, the 72 dpi and 144 dpi have the same resolution, but are mapped at different scales.