What does this format store?+
ARW is Sony Alpha raw image storage for compatible cameras. It retains image data for later development with capture metadata, instead of only a finished display image. The raw processor’s camera profile and rendering choices affect the output, so the same original can yield different colours or tone in different applications.
How does compression affect quality?+
Sony documents uncompressed, lossless-compressed and compressed recording options on supported models. Some lossless modes also offer image sizes. Availability and precision depend on the camera and settings; .arw alone neither identifies compression nor promises every stored sample is unchanged.
Are compressed and lossless-compressed ARW identical?+
They are different recording choices. Sony labels lossless compression separately; supported modes and sizes vary by camera. Inspect the actual setting rather than treating all ARW as one codec mode.
What should I check before opening the file?+
Check the exact camera model and recording mode in the processor’s support list. Raw support is model-specific, even when the extension is recognised. Viewing an embedded JPEG preview does not prove the sensor data has been decoded.
What changes when I export to another format?+
Raw-to-image export develops the data: white balance, colour mapping and tone become part of the pixels. Grayscale, palette and SDR targets can discard additional information. Keep the original; converting a rendered image back into a raw container cannot reconstruct the capture.
When is this format useful?+
Use the raw original for repeated photographic development when exposure interpretation and colour decisions need to remain flexible. Export JPEG for an opaque delivery image or a suitable high-precision raster for further editing. Those exports bake in processing choices and cannot recreate the original sensor data, calibration or all vendor metadata.