How Image Format Conversion Works
When you convert an image, the converter decodes the source file into raw pixel data, applies any resize options, then re-encodes that pixel data in the target format. The output quality depends on both the source image and the target format's compression method.
Conversion via canvas strips metadata including EXIF data (GPS coordinates, camera model, date taken). If preserving metadata matters, use a dedicated tool that reads and writes EXIF headers directly.
Common Conversion Scenarios
PNG to JPEG — reduces file size for photographs at the cost of lossy compression. Transparent pixels are filled with the chosen background color (white by default). Use this when a photo-like PNG needs to load faster and transparency is not required.
JPEG to PNG — produces a lossless copy of an already-compressed image. File size almost always increases. Useful when the image must be edited further without accumulating generation loss, or when the destination requires PNG format.
Any format to WebP — WebP achieves better compression than JPEG or PNG at equivalent quality and is supported in all modern browsers. Use it as a default output for web publishing when you want smaller files without format-specific compatibility concerns.
HEIC to JPEG — converts iPhone photos from Apple's native HEIC format to the universally compatible JPEG. Works in Safari on macOS and iOS. Chrome and Firefox cannot decode HEIC natively.
Transparency and JPEG Background Color
JPEG does not support an alpha channel. Any transparent areas in the source image must be filled with a solid color before the image can be saved as JPEG. The converter defaults to white (#ffffff), which is correct for images that will be placed on a white background.
If the destination has a different background color — such as a dark page or a colored card — set the background color to match before converting. You can enter any hex color value in the color picker that appears when JPEG is selected.
PNG, WebP, and AVIF all support transparency. Converting between these formats preserves alpha channel data without any background fill.
AVIF and Browser Support for Encoding
AVIF is a modern image format based on the AV1 video codec. It achieves significantly better compression than JPEG or WebP at the same visual quality, making it valuable for high-resolution images and large galleries.
Canvas-based AVIF encoding requires Chrome 94+ or Firefox 113+. Safari can display AVIF images but does not support encoding via the canvas API as of 2025, so AVIF export falls back to WebP in Safari. For confirmed AVIF output, use a command-line tool or server-side converter.