dcraw (pronounced “dee-see-raw”) is a legendary, open-source command-line utility developed by Dave Coffin that decodes and processes RAW images from hundreds of digital camera models. Because it is minimalist, blazing fast, and highly predictable, it has long served as the underlying backend engine for many advanced graphical RAW processors like RawTherapee and Darktable.
Mastering dcraw requires using specific terminal flags to manually control color correction, white balance, and demosaicing. Basic Inspection & Information
Before converting an image, you can use dcraw to inspect file properties and extract low-resolution previews without running a full extraction.
dcraw -i photo.CR2 — Identify file: Verifies if dcraw can decode the file and prints the camera model.
dcraw -i -v photo.NEF — Verbose metadata: Dumps detailed metadata including exposure time, aperture, ISO, and timestamp.
dcraw -e photo.ARW — Extract thumbnail: Instantly rips the camera-generated, embedded JPEG thumbnail from the RAW file. Color & White Balance Management
RAW files natively lack color structure and look heavily green or dull until a white balance is applied.
dcraw -w photo.CR2 — Camera white balance: Uses the exact white balance settings used by the camera when the shot was taken.
dcraw -a photo.CR2 — Auto white balance: Computes an average white balance by calculating the color profile across the entire image.
dcraw -r 2.1 1.0 1.5 1.0 photo.CR2 — Manual multipliers: Sets explicit RGBG multipliers for custom color calibration. Interpolation & Demosaicing
Sensors capture RAW data using a mosaic pattern (like a Bayer filter). Turning these pixels into a full-color image requires an interpolation method.
dcraw -q 0 photo.CR2 — Bilinear interpolation: Fast but low-quality processing; ideal for quick proofs.
dcraw -q 3 photo.CR2 — AHD interpolation: Uses Adaptive Homogeneity-Directed interpolation to reduce color artifacts at edges.
dcraw -h photo.CR2 — Half-size image: Generates a 50% sized color image, processing twice as fast to save resources. Output Configuration
By default, dcraw exports images as low-bit format .ppm or .pgm files. You must instruct it to output high-fidelity assets for professional workflows.
dcraw -T photo.CR2 — TIFF export: Generates a standard TIFF file instead of a PPM file.
dcraw -6 photo.CR2 — 16-bit output: Outputs 16 bits per sample instead of 8 bits to preserve full dynamic range.
dcraw -4 photo.CR2 — Linear 16-bit: Shorthand command that exports a raw, unsharpened, uncorrected 16-bit file with linear gamma.
dcraw -v -w -6 -T photo.CR2 — The “Standard Pro” workflow: A widely used combined script that outputs a verbose, camera-white-balanced, 16-bit TIFF image. Processing RAW Images in MATLAB – Imatest
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