Choose dimensions and format before lowering quality

Use JPG for photographs, PNG for transparency and text-heavy diagrams, and WebP for efficient web sharing. If an upload form specifies a format, its requirement takes priority.

A sensible order for reducing file size

1. Check the dimensions you actually need.
   A 4,000-pixel photo rarely improves a 1,200-pixel display. Resize first to avoid encoding detail that will never be shown.
2. Choose a format that matches the image.
   JPG suits continuous-tone photos; PNG suits logos, diagrams and transparency; WebP can efficiently handle both for modern web use.
3. Adjust quality last.
   Start around 80–85%, then inspect faces, text, fine lines and smooth gradients. Reduce quality gradually only when the file still needs to be smaller.

Format comparison

What SunData Tools actually does

The browser reads the selected image into a Canvas, draws it at the requested width and height, then creates a new download using your chosen format and quality. When JPG is selected, transparent areas are filled with white. The original file is not overwritten.

The image itself is not uploaded to a SunData server. Processing can still fail when a very large image exceeds the memory available to the browser; resizing the source with the device's built-in editor can help in that case.

Common problems

Text looks blurry

Screenshots and diagrams suffer when saved as a low-quality JPG. Try PNG or a higher-quality WebP.

A transparent background became white

JPG cannot store transparency. Choose PNG or WebP when transparency must remain.

The converted file is larger

The source may already be optimized. Keep the original or reduce the pixel dimensions. Changing formats alone does not guarantee a smaller file.

This guide is based on the implemented Canvas conversion behavior in SunData Tools and hands-on JPG, PNG and WebP testing. It does not override the requirements of a specific upload service.