Reference Images

A bunch of useful reference images for color calibration, and torture testing raw converter's interpolation algorithms

These are a group of synthetically generated reference images in the form of raw images, in DNG format. If you want TIFF format reference images, Bruce Lindbloom has some on his site. But be aware that there are significant differences between how TIFF and raw files are usually handled. Firstly, most images processing software uses very different default settings and secondly TIFF's are demosaiced, so you're not seeing the impact of the raw processor's interpolation algorithm.

These images were created by using an existing image as a template, but then replacing all of the image data with new data back calculated from the l*a*b* data of the GretagMacBeth chart, to the camera raw color space, using the color calibration matrix embedded into the original DNG file. And no, I'm not going to get into a debate about whether a raw file has a color space - go the the Luminous Landscape forums if you want to argue the number of angels that can fit on a pin head. 

Note these images are intended to be used at the "as shot" color temperature - the synthetic image generation code takes that into account as well. In addition to the GretagMacbeth chart, I also have monochrome step wedge charts. these are just created by stepping through the l values of the l*a*b* space. Exact values are in the calibration spreadsheet on the Calibration Spreadsheets page.

Inside of the LeicaM8Gretag ZIP file, there are three images:

  1. TestChart - this is in the native resolution of the camera, but is not level compressed. Generally, this is the right file to use with Lightroom and Aperture.
  2. TestChart_levelcompressed - this is a level compressed file. This file will only be there if the camera files are usually level compressed, e.g., the Leica M8 and the Nikon D80. You should use this as a last resort if your image processing software won't deal with the normal uncompressed version. E.g., Capture One 3.7.7.
  3. TestChart_CapOneV4 - this is a special purpose version that accommodates Capture One V4's peculiarities. Generally, this should only be used for Capture One V4, although any properly written DNG decoder will read it - e.g., Adobe Camera Raw and Lightroom.

For other cameras, there is just one file, at the native resolution of the camera.

Reference Calibration Images for the Leica M8

Color chart:LeicaM8Gretag.zip
Monochrome stepwedge chart: MonochromeTestChart.zip

Reference Calibration Images for the Canon G10

Color chart:CanonG10ColorTestChart.zip
Monochrome stepwedge chart: CanonG10MonoTestChart.zip

Reference Calibration Images for the Leica M9

The M9 charts will work with any of Lightroom, Capture One or Aperture. Each file is about 184K. There is also a link to DNG camera profile created from an image of a real GM24 chart using Adobe's Profile Editor.

Color chart:M9SyntheticGM24.dng.zip
Monochrome stepwedge chart: M9SyntheticGrey.dng.zip
DNG Camera Profile for Lightroom and ACR: M9DigitalCamera18Sept09.dcp