Image Converter and Resizer

The same picture can be stored in different ways, and the way decides the size and what survives. PNG keeps every pixel exactly and supports transparency. JPEG throws away detail the eye is poor at noticing and gets much smaller, but cannot be transparent. WebP does both jobs better than either and is understood everywhere current.

Converting means decoding the picture and writing it out again in the other way. Detail already thrown away never comes back, so a JPEG saved as PNG is a large file with the JPEG's losses still in it.

• Drop images onto the field, or click it to pick them. Several at once is fine, and they are all converted with the same settings.
• Pick the format to write. Quality only appears for JPEG and WebP, the two that can trade detail for size.
• One image fills the width and height with its own size, so they can be adjusted rather than typed from nothing. Several leave them empty, since they are not all the same size, and empty means each keeps the size it has.
• Change one of the two and, with the aspect ratio kept, the other follows.
• Two or more converted images can be downloaded together as a zip.

• An animation loses its animation. The browser hands over the first frame of an animated GIF or WebP, and that frame is what gets written.
• GIF holds at most 256 colours, so a photograph saved as GIF is reduced to a palette. It is meant for flat colour, not photographs.
• JPEG has no transparency. Anything transparent is filled with white rather than turning black.
• Making an image larger cannot add detail. It stretches what is there.