Image Resizer

Any time you map many pixels to fewer pixels, detail is merged—this is inherent to scaling, not a bug. Upscaling adds pixels the tool invents by interpolation, which can look soft if you blow up a small asset. Always keep a master file in the largest “clean” size you have before aggressive downscales.

If the source decoded with an alpha channel, the canvas keeps those transparent pixels through export. Fully opaque JPEG sources become opaque PNGs. If you see a unexpected background, the original format likely had no alpha (e.g. JPEG) or the image was flattened elsewhere.

When lock is on, changing width recomputes height (and vice versa) using the proportions of the image at load time. That reference is your file’s naturalWidth and naturalHeight after decode—useful when a storefront demands a fixed width but you do not want squashed products.

PNG is predictable for mixed content: crisp edges and alpha for UI. If you need JPEG for smaller photos, run this output through the Image Compressor and choose JPEG there—two quick steps beat a confusing matrix of options in one form.

Very large sources consume GPU/RAM while drawing; if the tab freezes, try a smaller source or close other heavy tabs. Mobile Safari generally works but may throttle background tabs—finish the resize while the page stays foregrounded.

Yes: the export canvas width and height match the integers you enter (within valid positive range). Non-integer aspect results from lock mode are rounded to whole pixels to avoid blurry fractional canvas sizes in browsers.