Opening a .BAY file varies with your intended workflow, with the proper method being to load it into RAW editors like Lightroom or Camera Raw where decoding, RAW interpretation, white balance, and color profiling occur before you fine-tune exposure and export JPG/TIFF; if Adobe tools reject it, your Camera Raw likely doesn’t support that Casio BAY variant, so RawTherapee or darktable—which often support rare camera outputs—are strong alternatives, though quick-view tools like XnView MP or IrfanView may only show embedded previews; DNG conversion via Adobe’s tool sometimes improves compatibility, but not for every BAY type, and complete failure to open usually means unsupported RAWs, corruption, or SD card read issues, making a re-copy and re-test helpful.

If you want to see more information about BAY file information look at the website. Where the .BAY file came from decides whether it’s really RAW, because BAY is usually a Casio RAW photo but may also be mislabeled or proprietary; if taken straight from a Casio SD card, use RAW editors like Lightroom, Camera Raw, RawTherapee, or darktable, as simple viewers often fail or show previews only, but if the file comes from apps, CCTV, dashcams, downloads, or email, it may be renamed, requiring the originating software, and BAY files from backups or recovery folders may be incomplete or lacking .THM/.JPG sidecars, producing color issues or read errors unless re-copied, so the source ultimately determines whether you handle it as a standard RAW or a proprietary file.

A .BAY file in Casio’s RAW format stores the camera’s sensor readings arranged in a Bayer-like mosaic where each site records only one color, requiring demosaicing to produce full-color pixels; it maintains higher-bit-depth information for stronger highlight/shadow retention and broader editing latitude, includes metadata such as exposure settings and white balance to guide initial rendering, and often holds an embedded JPEG preview that basic viewers display, which can look flat or off-color compared to a correct RAW-developed output.

A .BAY RAW file doesn’t hold the fully processed scene that a JPG/PNG would, because the camera only records raw brightness samples and metadata instead of committing to color, contrast, sharpening, or noise reduction, leaving software to demosaic and apply tone and color adjustments, which is why unprocessed views often look dark or muted, and although an embedded JPEG preview may exist, it is only a small thumbnail and not the finished image itself.

When you open a .BAY file, the software rebuilds the picture step by step rather than presenting a finished output, starting with decoding the BAY format (model differences causing some apps to fail), then demosaicing the single-color-per-photosite grid into RGB pixels, applying white balance and a camera/profile transform, mapping high-bit data with a tone curve to brighten and normalize the look, and often adding sharpening, noise reduction, and lens corrections, producing a rendered preview that becomes permanent only upon export, while missing support for that BAY variant results in errors, odd hues, or showing only the embedded JPEG preview.