Through the lens analysis option, optical distortions of the barrel or pincushion type, and chromatic aberrations can be quantified.
The analysis meets the recommendations of ISO 19084 Photography - Digital cameras - Chromatic displacement measurements and ISO 17850 Photography - Digital cameras - Geometric distortion (GD) measurements to establish these metrics.
For the analysis, the chart proposed in ISO 17850 is used, consisting of 300 disks organized in 20 columns and 15 rows, the optical distortion estimations are made on the diagonal in the upper right corner.
Only images smaller than 1500 pixels on the larger side can be used. If working from raw images, you should generate images at this size from the raw processor to avoid sampling errors when reducing the images.
The graphs provided are as follows:
- CARG (Chromatic Aberration Red-Green and Blue-Green) Shows the distance between red and green channel (in red line) and the distance of blue from green (in blue line) along the diagonal of the upper right corner. The most extreme values for each channel are represented by the metrics BG Max and RG Max.
- CABGr (Chromatic Aberration Red-Green and Blue-Green Radial) Shows the distance between these channels but based on the radial metric described in ISO 19084.
- DISTORTION Shows the distance along the upper right diagonal of the position of the disks obtained in the image with respect to their expected position. The distortion is classified by Barrel if it is negative and Pad if it is positive.
- VISUAL-CABG and VISUAL-CARG It is the synthetic representation of the disks used and their deviation. The number accompanying each disk is the distance between the disks.
- VISUAL-DIST It is the synthetic visual representation of the optical distortion between the disks deduced from the image and the expected disks based on the distance from the image center. The accompanying number is the distance between the pair of disks.
Download the test chart
At this URL:http://imageqa.jpereira.net/charts/carta_ISO_19084.pdf
You can download a test chart to be printed in A3 black and white. The chart should be mounted on a very flat surface, to avoid distortions when capturing it.