Reduce image file size without surprises

Image dimensions and image file size are different things. A 1,200-pixel picture can be a small or large download depending on its content, format and encoding. Change one setting at a time so you know what improved the result.

Start by keeping the dimensions

Choose your source in the image compressor and leave Maximum width at zero. This keeps the decoded pixel dimensions. Try WebP or JPEG at 80% quality, then compare the actual output size. Inspect the preview around detailed foliage, small objects and smooth color gradients.

If the image still looks good, reduce quality in small steps. If important details break up or text becomes hard to read, raise it again. Quality values describe the browser encoder setting; an 80% setting does not mean 80% of the original bytes or 80% of visual detail.

When a smaller width makes sense

If the picture will be displayed at a narrow width, exporting the full camera resolution can waste bytes. Setting a maximum width reduces the pixel dimensions while keeping the image proportions. It does not enlarge images that are already smaller than the limit.

For example, a 1,536 × 1,024 sample limited to 960 pixels wide becomes 960 × 640. That is a resizing operation as well as a compression operation. Keep Maximum width at zero if your destination requires the original dimensions.

How target size works

The optional target is entered in KiB: one KiB is 1,024 bytes. PixelDesk tries lower quality settings, within the available range, to find a result at or below that size. Your chosen quality is the upper limit. It will not silently reduce dimensions to meet a target.

Some targets are too small for the selected dimensions. If minimum quality still exceeds the target, the result says so. You can accept that output, use a smaller maximum width, or choose a different format. Always check appearance as well as bytes.

Why an output can be larger

An original image may already be efficiently compressed. Re-encoding it at a higher quality, converting a simple image into another format, or changing encoder behavior may increase its size. PixelDesk reports both smaller and larger outputs honestly. There is no benefit in downloading a larger replacement unless another property, such as compatibility, improves.

Transparency and source quality

JPEG uses the selected background color for transparent areas. WebP can preserve transparency when the option is selected. Neither format can recover detail that is missing from the source. Save your original file and make a separate optimized copy.