DCTau: A photographer's tool for testing digital cameras based on HALCON

DCTau by Anders Uschold, Munich, provides a standardized test to evaluate digital cameras with only minor interaction by the operator. One of the design objectives was to produce results for the low-skilled consumer as well as for the high-skilled professional. The tested features are

• resolution and deviation
• number of reproduced lines
• orientation of best and worst resolution
• Moire-effects depending an spatial resolution and line orientation
• contrast
• noise over the whole range of intensities
• sharpening effects depending on local contrast and color
• optical distortion of the image (for zoom lenses depending on different focal lengths)
• loss-of-brightness from center to corner by the use of different apertures

All features are examined in the three color channels (RGB) and the gray channel. The tests concerning the resolution use different line targets with increasing spatial frequency and a "Siemensstern". Noise, color, contrast, and sharpening use the standardized IT8 color chart. Loss-of-brightness needs a simple gray ramp. All these tests have been realized based on the HALCON programming environment, which allows a quick adaption to "difficult" test candidates.

The subsequent analysis and evaluation of the test results is done using Lotus 1-2-3.

DCTau will be presented at the CeBit 1998 (Hannover) in cooperation with the German photographer's magazine "fotoMAGAZIN".

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