The selected image is decoded and rendered to an HTML canvas in the browser. Resizing uses high-quality browser interpolation, and JPEG or WebP quality controls the encoder setting used for the downloaded file.
JPEG cannot preserve transparency, so transparent pixels receive a white background. File size depends on image detail, dimensions, format, and encoder implementation.
Questions
Image Format Converter FAQ
What happens to transparency when converting to JPEG?
JPEG has no alpha channel, so transparent pixels are placed on the selected white background.
Which image format should I use?
JPEG suits photos, PNG suits lossless graphics and transparency, and WebP often provides smaller web files with either lossy or lossless encoding.
