PNG isn’t a popular camera capture format because it misses the main advantages of both JPEG and RAW.

JPEG is used because it makes much smaller files, which saves card space and speeds writing. RAW is used because it preserves the sensor data for later editing. PNG sits awkwardly in between: it is lossless relative to an already processed image, but the camera still has to demosaic, choose white balance, apply sharpening and noise reduction, and reduce bit depth before saving. So compared with RAW, important editing flexibility is already lost.

That means PNG would usually produce files closer in size to RAW, but without RAW’s post-processing benefits. Compared with JPEG, it would be much larger without offering the same practical savings.

Another issue is metadata: JPEG and RAW workflows commonly rely on EXIF data, while PNG has not traditionally had the same standardized EXIF support, which makes it less attractive for camera makers and photographers.

PNG is great for graphics, screenshots, and some scanned material, but for camera photos the usual tradeoff is JPEG for convenience or RAW for maximum image data.