Precise ROI selection is necessary to ensure an accurately measured dyanmic range using a linear chart such as the Xyla-26. The imaging system that captured the chart does not resolve all 26 patches. The steps below guide users on how to deal with such a situation using Imatest Master.
ROI Adjustment Steps
The steps below can be applied to any linear chart read using the Color/Tone Module. The image used for the demonstration is that of a Xyla-26 chart via Color/Tone Interactive.
1. In Color/Tone Interactive, read your image as a Linear grayscale:
2. Choose the number of patches accordingly.
3. Only 20 out of the 26 patches can be resolved. The image was lightened to aid with the ROI selection.
4. From here simply drag your mouse pointer to select the ROI. Please note the following:
- Make sure your ROI selection engulfs all the patches of the Xyla chart.
- Adjust the fill factor in accordance with the patches' size. In this case, we used a fill factor of 0.4.
- The edges and corners of the selection were adjusted(ROI fine adjustment) to narrow down the patches accordingly.
Here's the selection:
5. Click Yes, Continue to carry on with your test.
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