The Spilled Coins chart (a variant of the Dead Leaves chart) for measuring texture sharpness has several advantages over older Dead Leaves charts. Key features:
- The Scattered Coins pattern in the central region is almost perfectly scale-invariant (unlike conventional dead leaves charts), enhancing the accuracy and robustness of MTF measurements so they correlate well with other methods (such as the slanted-edge) for RAW images (which have no nonuniform or nonlinear processing).
- Maximum contrast range is 3:1, as called for in the CPIQ Phase 3 draft Texture Blur Metric draft specification.
- It is more uniform, i.e., is more shift-invariant than other Dead Leaves charts.
- It contains slanted edges (2:1 and 4:1 contrast) for convenient comparisons with the dead leaves pattern.
- The gray area to the left and right of the dead leaves pattern has the same mean density as the dead leaves pattern, allowing it to be used for effective noise PSD removal using the McElvain et. al. technique.
- Registration marks and 16 grayscale patches are included. The linear levels used to create the grayscale patches are 0 through 255 in steps of 17 (same as the Siemens Star chart in the draft of the upcoming ISO 12233 standard).
- Imatest Spilled Coins equivalent of the Image Engineering TE-265 referenced in the Skype spec is the Large, Matte ISC0024
| Spilled Coins chart sizes | Spilled Coins region | Printed region | Media size total |
|---|
| Large | 12" × 12"
305 mm × 305 mm | 22.4" × 16.8"
569 mm × 426 mm | 24" × 18"
610 mm × 458 mm |
| Medium | 8" × 8"
203 mm × 203 mm | 14.93" × 11.2"
379 mm × 284 mm | 16" × 12"
458 mm × 305 mm |
| Small | 6" × 6"
152 mm × 152 mm | 11.2" × 8.4"
284 mm × 213 mm | 12" × 10"
305 mm × 254 mm |
| X-Small (High Precision Transmissive) | 5.536" × 5.536"
141 mm × 141 mm | 9.25" × 7.75"
159 mm × 197 mm | 10" × 8"
254 mm × 203 mm
|
