dcraw

Section: User Commands (1)
Updated: March 3, 2015
Page Index

NAME

dcraw - command-line decoder for raw digital photos

SYNOPSIS

dcraw [OPTION]... [FILE]...

DESCRIPTION

dcraw decodes raw photos, displays metadata, and extracts thumbnails.

GENERAL OPTIONS

-v: Print verbose messages, not just warnings and errors.
-c: Write decoded images or thumbnails to standard output.
-e: Extract the camera-generated thumbnail, not the raw image. You'll get either a JPEG or a PPM file, depending on the camera.
-z: Change the access and modification times of an AVI, JPEG, TIFF or raw file to when the photo was taken, assuming that the camera clock was set to Universal Time.
-i: Identify files but don't decode them. Exit status is 0 if dcraw can decode the last file, 1 if it can't. -i -v shows metadata.
: dcraw cannot decode JPEG files!!

REPAIR OPTIONS

-I: Read the raw pixels from standard input in CPU byte order with no header. Use dcraw -E -4 to get the raw pixel values.
-P deadpixels.txt: Read the dead pixel list from this file instead of ".badpixels". See FILES for a description of the format.
-K darkframe.pgm: Subtract a dark frame from the raw data. To generate a dark frame, shoot a raw photo with no light and do dcraw -D -4 -j -t 0.
-k darkness: When shadows appear foggy, you need to raise the darkness level. To measure this, apply pamsumm -mean to the dark frame generated above.
-S saturation: When highlights appear pink, you need to lower the saturation level. To measure this, take a picture of something shiny and do dcraw -D -4 -j -c photo.raw | pamsumm -max
: The default darkness and saturation are usually correct.
-n noise_threshold: Use wavelets to erase noise while preserving real detail. The best threshold should be somewhere between 100 and 1000.
-C red_mag blue_mag: Enlarge the raw red and blue layers by the given factors, typically 0.999 to 1.001, to correct chromatic aberration.
-H 0: Clip all highlights to solid white (default).
-H 1: Leave highlights unclipped in various shades of pink.
-H 2: Blend clipped and unclipped values together for a gradual fade to white.
-H 3+: Reconstruct highlights. Low numbers favor whites; high numbers favor colors. Try -H 5 as a compromise. If that's not good enough, do -H 9, cut out the non-white highlights, and paste them into an image generated with -H 3.

COLOR OPTIONS

By default, dcraw uses a fixed white balance based on a color chart illuminated with a standard D65 lamp.

-w: Use the white balance specified by the camera. If this is not found, print a warning and use another method.
-a: Calculate the white balance by averaging the entire image.
-A left top width height: Calculate the white balance by averaging a rectangular area. First do dcraw -j -t 0 and select an area of neutral grey color.
-r mul0 mul1 mul2 mul3: Specify your own raw white balance. These multipliers can be cut and pasted from the output of dcraw -v.
+M or -M: Use (or don't use) any color matrix from the camera metadata. The default is +M if -w is set or the photo is in DNG format, -M otherwise. Besides DNG, this option only affects Olympus, Leaf, and Phase One cameras.
-o [0-6]: Select the output colorspace when the -p option is not used:
0   Raw color (unique to each camera)
1   sRGB D65 (default)
2   Adobe RGB (1998) D65
3   Wide Gamut RGB D65
4   Kodak ProPhoto RGB D65
5   XYZ
6   ACES
-p camera.icm [ -o output.icm ]: Use ICC profiles to define the camera's raw colorspace and the desired output colorspace (sRGB by default).
-p embed: Use the ICC profile embedded in the raw photo.

INTERPOLATION OPTIONS

-d: Show the raw data as a grayscale image with no interpolation. Good for photographing black-and-white documents.
-D: Same as -d, but with the original unscaled pixel values.
-E: Same as -D, but masked pixels are not cropped.
-h: Output a half-size color image. Twice as fast as -q 0.
-q 0: Use high-speed, low-quality bilinear interpolation.
-q 1: Use Variable Number of Gradients (VNG) interpolation.
-q 2: Use Patterned Pixel Grouping (PPG) interpolation.
-q 3: Use Adaptive Homogeneity-Directed (AHD) interpolation.
-f: Interpolate RGB as four colors. Use this if the output shows false 2x2 meshes with VNG or mazes with AHD.
-m number_of_passes: After interpolation, clean up color artifacts by repeatedly applying a 3x3 median filter to the R-G and B-G channels.

OUTPUT OPTIONS

By default, dcraw writes PGM/PPM/PAM with 8-bit samples, a BT.709 gamma curve, a histogram-based white level, and no metadata.

-W: Use a fixed white level, ignoring the image histogram.
-b brightness: Divide the white level by this number, 1.0 by default.
-g power toe_slope: Set the gamma curve, by default BT.709 (-g 2.222 4.5). If you prefer sRGB gamma, use -g 2.4 12.92. For a simple power curve, set the toe slope to zero.
-6: Write sixteen bits per sample instead of eight.
-4: Linear 16-bit, same as -6 -W -g 1 1.
-T: Write TIFF with metadata instead of PGM/PPM/PAM.
-t [0-7,90,180,270]: Flip the output image. By default, dcraw applies the flip specified by the camera. -t 0 disables all flipping.
-j: For Fuji Super CCD cameras, show the image tilted 45 degrees. For cameras with non-square pixels, do not stretch the image to its correct aspect ratio. In any case, this option guarantees that each output pixel corresponds to one raw pixel.
-s [0..N-1] or -s all: If a file contains N raw images, choose one or "all" to decode. For example, Fuji Super CCD SR cameras generate a second image underexposed four stops to show detail in the highlights.

FILES

:./.badpixels, ../.badpixels, ../../.badpixels, ...

List of your camera's dead pixels, so that dcraw can interpolate around them. Each line specifies the column, row, and UNIX time of death for one pixel. For example:

 962   91 1028350000  # died between August 1 and 4, 2002
1285 1067 0           # don't know when this pixel died

These coordinates are before any stretching or rotation, so use dcraw -j -t 0 to locate dead pixels.

AUTHOR

Written by David Coffin, dcoffin a cybercom o net