A screenshot and a camera photo of similar dimensions can end up wildly different in file size, and the compression that works well for one doesn't always suit the other. The difference comes down to what kind of visual content each one actually contains.
A photo of a person, a landscape, or a product has countless subtle color gradients, textures, and lighting variations — exactly the kind of complex, gradual detail that photo compression is built to handle efficiently, discarding imperceptible information while keeping the image looking sharp.
A screenshot of a chat conversation, a spreadsheet, or an app interface is largely solid blocks of color with crisp, hard edges — text, icons, flat backgrounds. This is a very different kind of image data than a photo, and it often compresses more efficiently with a different approach that's better suited to sharp edges and flat color regions.
Applying photo-style compression to a screenshot full of small text can sometimes introduce subtle blurring or color artifacts around the text edges — exactly where you need things to stay crisp for readability. This is why a screenshot of an important document or conversation is worth double-checking after compression, more so than a typical photo.
Because of their flat-color, low-detail nature, screenshots frequently start out significantly smaller than a camera photo of similar pixel dimensions, even before any compression is applied — so the size problem with screenshots is usually less urgent than it is with photos and videos.
For photos, aggressive compression is usually safe and often barely noticeable. For screenshots, especially anything with important text, it's worth using a lighter compression setting and checking the result stays crisp before sending it somewhere the text needs to remain fully legible.
Not every image needs the same compression treatment — a quick awareness of what kind of image you're dealing with helps you avoid either wasting file size or losing readability where it actually matters.