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Imatest Documentation

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<strong>Imatest</strong> <strong>Documentation</strong><br />

Targets<br />

Charts are mounted on 40x60 inch (100x150 cm) or 30x40 inch (75x100 cm) 1/2 inch (1.25 cm) thick foam board, which is<br />

lightweight, rigid (unlikely to warp), and easy to find at art supply shops. The images below show entire targets. Framing would<br />

normally be tighter for test images (much tighter for the Q-14, ColorChecker, and OECF targets). In some cases, the charts are<br />

mounted on neutral, middle gray (~18% reflectance) mat board, which is attached to foam board, to ensure correct exposure in<br />

cameraphones and webcams with autoexposure.<br />

Charts are mounted using permanent double-sided tape or spray adhesive, available from hardware and art supply stores. We have<br />

used 3M 45 and 3M Photo Mount sprays, both of which are "Photo safe." 3M Super 77 is not labeled "Photo safe," (and can't<br />

be sold in California), but it should be OK for attaching gray mat board to foam board.<br />

Sharpness targets<br />

The SFRplus chart, introduced with <strong>Imatest</strong> 3.2, features automated region detection for sharpness and other measurements. It<br />

offers numerous advantages over the well-known ISO 12233 chart, particularly more accurate measurements due to<br />

reduced contrast, sufficient regions to produce a good lens response map, and compatibility with automatic region detection.<br />

SFRplus also measures distortion, tonal response, gamma (contrast), and color accuracy (with the optional color chart shown<br />

below). It is especially useful for automated testing. SFRplus charts are available for purchase.<br />

SFRplus color chart<br />

Two additional sharpness targets are also used in the <strong>Imatest</strong> lab, though less frequently than the SFRplus chart. Both consist of<br />

several charts printed on Epson Enhanced Matte (Ultra Premium Presentation - Matte) paper, which resolves detail as well as<br />

semigloss and glossy inkjet papers, but is much less susceptible to glare. These charts support SFR as well as several Rescharts<br />

modules (SFR, Log F-Contrast, Log Frequency, and Star Chart).<br />

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