Check size and transparency first
This retained preparation workflow accepts an opaque, 8-bit RGB or RGBA PNG, up to 4 MiB and 4,194,304 pixels. It rejects animated PNG, transparency and orientation metadata. Its maximum output side is 2,048 pixels; smaller images are never enlarged.
A concrete sizing check
The synthetic sample is 480 × 320 pixels. A maximum side of 240 should produce 240 × 160 pixels. A maximum side of 1,024 should keep 480 × 320. A successful result must decode in its selected format; output bytes may be larger than the source.
Review the result
The browser raster and export do not promise color-profile or metadata preservation. Cancel discards a pending result; browser image encoding may finish before its temporary resources can be released. Reset releases the selected input and displayed canvases. This workflow has no automatic input storage or upload.
Troubleshooting
If inspection rejects the PNG, check its actual structure, opacity, bit depth, animation/orientation metadata and the 4 MiB / 4,194,304-pixel limits. Use a whole-number maximum side from 1 to 2,048. The selected file is retained when a pending result is cancelled; choose Prepare image again for an explicit retry.
Questions
Why does a 480 × 320 image stay that size when the maximum side is 1,024?
This workflow fits within a bound without enlarging smaller images. A side of 240 yields 240 × 160, while 1,024 keeps the original 480 × 320 dimensions.