General information[]

CHDK supports two raw formats: DNG and "CHDK Raw".

  • DNG is open industry standard, and is compatible with many standard image processing programs. To shoot DNG, you must first use 'create badpixel.bin' in the raw menu. See the CHDK User manual for more information.
  • "CHDK raw" is not in any standard format. Technically it's not a format at all, it's just a dump of the camera sensor. This means that different models raws are in different formats, and programs which support CHDK raw need to be updated for new models. Some programs which do support CHDK raws from many models are listed in Software#RAW_related.

Note It is important to understand that the file extension is not the same as the file format. CHDK raws and DNGs are frequently saved with a .CRW or .CR2 extension, but they are NOT in Canon formats that typically use these extensions. In windows, file extensions may be hidden, and the "file type" display by windows is in fact the extension, not the format of the data inside the file.

If you are new to CHDK RAW, please take a look at this : CHDK Forum RAW for Beginners

More good discussion about raw processing may be found in the CHDK RAW subforum


Raw conversion section of the software page

Technical details of CHDK raw[]

The Frame buffers page describes the layout of RAW data. Individual sensor sizes may be found in platform/<model>/platform_camera.h

From the old FAQ entry, needs sorting and cleaning![]

  • convert it to the standardized DNG digital negative format using the DNGForPowerShot converter. The DNG files then can be processed with nearly every RAW converter on the market, including Adobe Lightroom and Apple Aperture (read notes on the bottom).
(Note that DNG4PS will copy the EXIF data from the RAW file's corresponding JPG file to the new DNG file. The RAW files themselves do not contain any EXIF-header info until this is done. If you are using some of the new builds of CHDK with features like shutter-speed and aperture overrides then the original JPG EXIF header, from which this data is taken for the DNG RAW file's EXIF-header, may not reflect these new values that are outside of the normal bounds of your Powershot's EXIF information. A small utility was created that allows you to process your JPG files to update appropriate EXIF fields with these non-standard CHDK override shutter-speed, aperture, and ISO values. You can find the latest version of this utility at the new CHDK Forum at the end of this discussion thread Converting CHDK EXIF info to Standard EXIF. Read the full thread on how to install and use it as it also requires the installation of EXIFTool and copying then renaming the main "exiftool(-k).exe" file to just "exiftool.exe". Installation and usage info is on a link in that thread to the original Auto ISO Patcher that was edited for this purpose.)
Direct link to the executable: Auto CHDK to EXIF - 2.61MB (this v1.3 'complete' archive already include the ExifTool executable, read the included README.txt file); see also the ISO80-issue discussion in the forum.
  • convert it to the DNG format using DNG4PS-2 (homepage) converter. It is newer and much more optimized and feature packed. Supports a number of Canon Powershot models and the Windows, Linux and MacOSX platforms.
  • process the RAW files directly with appropriate converters. Right now, this applies to converters which are based on David Coffin's DCRaw. Here are some free examples:
    • UFRaw
    • iRAW (Mac OSX, Windows, Linux)
    • Raw Therapee (Windows, Linux)
    • Shotwell (Linux)
    • Picasa 2.7 and above
    • Faststone Image Viewer displays the RAW files if you want to browse them A very good image viewer/converter. It also has most of the usual editing tools (brightness, constrast, gamma, hue, rotations, cropping, etc.).
    • Xnview, a free image viewer/editor, also handles RAW files well and is available for many platforms (Win/Mac/Linux). It has advanced filtering/editing functions.
    • LightBox (Freeware) and LightBox Plus($) A fairly decent editor for RAW files that also seems to open all CHDK RAW file formats. It has some nice shadow and white-balance adjustment tools (even in the FreeWare version) that exceed what you might find in PhotoShop or other editing programs.
    • Rawker freeware, MacOS X
    • ChocoFlop free and commercial versions available, Mac OS X

[Note that the above mentioned steps may not work for all cameras yet. Especially the A640 CHDK program was just recently added, so the RAW converters may not support it yet.
If you know that it works or have further information, please delete this paragraph]

The A630 and A640 are first mentioned in DCRaw ( source code at version 8.70 (current as of June 17, 2008 is version 8.86), so may be supported (I don't have these cameras to test with). If you want to use DCRaw directly (from command line), you can download the source code from the above link and compile, or download binaries for both Windows and Mac OS X from

The A570, A630 and A640 is also supported in Raw Therapee ( Its available for Windows and Linux.

DNG For PowerShot supports A610, A620, A630, A640, A710 IS, S2 IS, S3 IS since v1.1

DNG4PS-2 (v0.2.2beta-24) supported cameras: A610, A620, A630*, A640, A710 IS, S2 IS*, S3 IS, A700*, G7*, A560*, A570 IS*, IXUS 700*, IXUS 70*, IXUS 800*, A720 IS, S5 IS, IXUS 950, A650 IS, A460, SD800 IS, A530, A540.

  • - supported without correct color camera profile. If you have correct camera profile for one of these cameras or you want to calculate it, read this forum topic.

There is also a hack for RawShooter (thanks PhotoHans). Examine a DNG file to obtain the exact name eg. 'PowerShotS3IS' (no spaces) open RawShooter.exe in an editor and change 'PowerShot G5 ' to PowershotS3IS and save. Make sure file length is unchanged and make a backup before you begin.

These are some Mac programs which read the RAW files (.CRW) produced by CHDK. From least to most hassle (and decreasing expense):

Fast, sweet WB & other options.
An extremely capable editor, better than PhotoShop in many ways. Full RAW file support, interpolation methods, WB, contrast, clipping, color correction, contrast, auto-white-point, clipping limits, assign ICC color-profiles, define curves on all or each channel, save favorite presets, etc. Does not export to DNG format, but DNG format is only needed by other less-capable editors so you don't need this feature. You do all your RAW editing right within PhotoLine. Converting to DNG format is only needed for those editors that can't deal with CHDK's unique RAW format natively. PhotoLine is not thus encumbered.
Promising. Slower; its WB options not yet satisfactory for some. Does not export to DNG format.
Does many conversions, great for automation, but you're working blind. This page gives examples of its parameters.
This is a GUI-Version of the above mentioned dcRAW. Works with my A710is (and I guess with most other Powershots)
These export JPG, and some TIFF and DNG

How to make converted DNG files work with Apple Aperture

  • UPDATE: Aperture 2 now has Baseline DNG support. You can work with those converted RAW file without any plist hacks with Aperture 2.

By default the converted RAW files do not work with Apple Aperture, but with a little plist hack you can organize and edit them in Aperture!

  • Convert the RAW files with DNG4PS2. There is now a Mac native Intel binary available to do this at [1]. This excellent freeware program batch processes CRW files into DNGs which can be imported directly into Aperture 2.1, but the white balance is not as shot. The current beta of DNG4PS-2 for Mac (as of 14-Apr-2008) will crash on completion of the last file on Mac OSX 10.5. This is a minor issue rather than a showstopper, as you've already processed the batch.

(If you want to run the Windows version instead, it also works with emulator software Darwine or CrossOver Office )

  • In the finder, navigate to System/Library/Frameworks/ApplicationServices.framework/ Versions/A/Frameworks/ImageIO.framework/Versions/A/Resources/Raw.plist

If you are using Mac OS X 10.5 Leopard, the file is in /System/Library/CoreServices/RawCamera.bundle/Contents/Resources/Raw.plist

  • Open up the Raw.plist with any text editor (I use SubEthaEdit) or an advanced plist editor.
  • Add the follwing line into Raw.plist:
<key>Canon PowerShot A610</key>  <string>Canon PowerShot G6</string>

(Change "Canon-PowerShot A610" into the name of the camera you have. I also tried the S70 and 350D strings which also works. You can examine different Canon cameras' strings. Colors will be offset since Aperture treats your converted DNG files as the camera you assigned.) (2008/1/16 - Removed the dash from the <key> above from its previous, nonworking form <key>Canon-PowerShot A610</key> <string>Canon-PowerShot G6</string>. Make sure to add the key above the Canon PowerShot G6 entry in Raw.plist)

  • Save the edited Raw.plist
  • Now you can load all the converted DNG files into Apple Aperture.

For more detailed discription on editing the Raw.plist you may look at here.

> hi! only DCRAW and RAW THERAPEE works with my S2 IS raw files, but imho (for me) RAW THERAPEE is can edit your foto before you save it (i.e. in TIFF). So, don't waste your time:) Download RAW THERAPEE for your S2 IS raw files :)

There isn't real support of PowerShot G7 in dcraw (and in based ot it - libraw, libopenraw, ufraw, RawStudio, etc). The color matrix values used from A640 and it's wrong for G7.

As a solution you may 1) Save as DNG at camera by option in CHDK menu - "Raw Parameters". Or - 2). Convert your CRW to DNG by 'dngconverter' utility (from digiKam or using dcp profile - Canon_PowerShot_G7.dcp . Or - 3) Use DNG4PS-2 to convert CRW files to DNG.

DNG file you can open in any raw image processing program.

> Added comment. SD800IS doesn't work with G6, S70, or 350D settings map. Briefly flashes pic in Aperture (with weird aspect ratio) then you get the Unsupported Image Format message.

Fine-tuning Adobe Camera Raw's color rendition of CHDK-generated DNG files

"DNG profiles" are Adobe's solution to this. See this pagefor an explanation (and downloads of profiles for various cameras).