Why transparent PNGs sometimes turn black
PNG can store an alpha channel: pixels can be fully or partly transparent. JPG stores opaque RGB pixels and cannot retain an alpha channel. Some converters replace transparent pixels with black by default, while others use white. The result is not a defect in JPG itself; the conversion process needs an explicit background color.
Convert your PNG to JPG in five steps
- Open the free Toolmintly image converter and select the PNG file. You can add several files if needed.
- Choose JPG as the output format.
- Set the background for transparent pixels to white, another solid color, or the color required by your destination.
- Choose a suitable JPG quality level, then select Convert images.
- Check the preview and extension before downloading. The file is actually re-encoded as JPG, not merely renamed.
What about semi-transparent shadows and edges?
Soft shadows, anti-aliased logo edges and transparent overlays are composited onto the selected background. Try the same color as the page or listing where the JPG will appear. If a logo needs to work on multiple backgrounds, keeping the original transparent PNG or converting to WebP may be preferable.
Can converting reduce the file size?
For photographs, JPG is often smaller than PNG at an acceptable visual quality because JPG uses lossy encoding. A tiny line-art image or text-heavy screenshot may not benefit. A conversion is not a guarantee of savings, and repeated lossy re-encoding can reduce fine detail. Keep the original PNG as a master file.
When not to choose JPG
Do not use JPG if the receiving website specifically requires PNG, or if you need transparent pixels. Use the JPG vs PNG vs WebP guide to decide. For a size limit, the image compressor can test a target KB size on JPG/WebP, optionally reducing pixel dimensions only if you enable it.
Where does the file go?
Toolmintly converts supported JPG, PNG and WebP images in the browser. It does not intentionally upload selected images to an application processing server. Canvas re-encoding may remove image metadata such as EXIF. See the privacy policy and inspect sensitive files before sharing them.