Adjust image compression quality by inspecting text, edges and textures. Find a usable balance instead of relying only on a smaller file size.
Define what must remain readable
Not every part of an image has the same importance. In a product photograph, the shape and texture may matter most. In a screenshot, small labels can be the entire point of the image. Decide what viewers need to recognize before changing the quality setting.
Open the original at its intended display size and identify two or three areas to compare. Include a sharp edge, a detailed area and a smooth region if possible. This gives you a consistent way to judge successive exports.
Start with a moderate setting
The compressor starts at 80% quality. Generate that result before moving the slider much lower. Read the original and output file sizes, then inspect the areas you selected. If the result looks suitable, a small additional reduction may be worth comparing, but it is not required.
Lower settings can introduce softened details, blocks or ringing around edges. Increase quality when these changes interfere with reading or recognition. The slider does not express a guaranteed percentage of original detail preserved.
Consider dimensions as a separate control
This compressor does not reduce width or height. A very large photo can remain a large file even after a significant quality adjustment. If the destination displays it at a much smaller size, prepare suitable dimensions with Image Resizer first.
Do not make the dimensions so small that you later need to enlarge the image again. Plan the intended display before producing your delivery copy. Keeping an untouched original allows you to repeat the process with better settings.
Save only after visual inspection
Download the candidate and reopen it in your usual viewer. Check the important areas at the size other people will use, especially lettering and thin lines. Choose the result that is both practical to transfer and clear enough for its purpose. There is no single quality value that guarantees the best result for every image.