Imatest Transmissive SFRplus Test Chart
The Transmissive SFRplus test charts can be used with the SFRplus module in Imatest 3.2 or later to measure MTF, lateral chromatic aberration, distortion, tonal response, and color accuracy. The SFRplus module features fully automated region-of-interest detection. The SFRplus chart offers significant advantages over commonly used charts such as the ISO 12233 chart, including:
- Better use of chart area
- The ability to produce a map of sharpness over the sensor surface
- Better measurement accuracy due to the lower contrast
- Full support for automated testing
Download PDF Info Sheet. See our Reflective SFRplus charts here.
Description
Video (Watch on our site)
Contrast Ratio Options
- 4:1 contrast ratio complies with the contrast requirements of the IS0 12233:2014 and ISO 12233:2017 standards. Recommended.
- 10:1 and 2:1 contrast ratios. Uses of both contrast levels improves ability to analyze non-linear signal processing, especially sharpening, which affects 10:1 contrast ratio edges more strongly than 2:1 edges
- 10:1 contrast-only. Used in earlier versions of SFRplus charts to give results closer to ISO 12233:2000, which had excessive contrast (≥40:1) that often caused the image to saturate, resulting in erroneous MTF measurements.
Substrate Options
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- Inkjet on Matte Paper can be easier to light because it has less specular reflection than the semi-gloss paper. The MTF is slightly less than semi-gloss paper and does not have as deep dark tones on the stepchart.
- Inkjet on Semi-gloss Paper has slightly higher density than matte, has deeper black tones on the stepchart. Due to the difficulty of lighting this evenly without introducing specular reflections, we do not recommend Semigloss targets.
- LVT Color Film offers the best possible density range, low noise, color and fine detail.
- LVT Black & White Film provides a wide density range, low noise, and fine detail. The edges have an MTF50 >= 10 cycles/mm, which is approximately two times better than the best inkjet charts. For more information, please see our Transmissive Chart Quality Comparison. The large patterns are fine enough to produce good results with up to 30 megapixel cameras…..
- The SFRplus target is also available as Chrome on Glass, Photographic, High Stress Targets, and Infrared / NIR Targets.
Square Grid Dimensions Options
- 5 x 9 squares grid dimension is recommended for for typical DSLR formats with aspect ratios of 3:2 and typical HDTV formats with aspect ratios of 16:9.
- 5 x 7 squares grid dimension is recommended for typical compact camera formats with aspect ratios of 4:3.
Size Options by Substrate (Total Size and Active Area Dimensions)
Inkjet charts are available in five main sizes with variations depending on the grid dimensions selected. It is recommended that the medium sized charts be used to test imaging systems with sensors up to 14MP, the large charts be used for testing of sensors above 14MP and up to approximately 28MP, and the extra-large charts be used for sensor sizes above 28MP and up to 48MP.
The active area of the chart includes white space above and below the top and bottom distortion bars. It is slightly larger than the printed area, which is bounded by the distortion bars on top and bottom. White space is included in active area because test images of the chart must include this white space in order to enable automated processing in SFRplus software.
Inkjet Chart Sizing: Paper Size (Including Margin) and Active Area
| 5 x 9 Squares | 5 x 7 Squares | |||
|---|---|---|---|---|
| Paper Size | Active Area | Paper Size | Active Area | |
| X-Small | 21.59cm x 38.1cm (8.5″ × 15″) | 19.76cm x 35.56cm (7.778” x 14”) | 21.59cm x 25.4cm (8.5″ × 10″) | 16.33cm x 22.86cm (6.429” x 9”) |
| Small | 35.56cm x 60.96cm (14″ × 24″) | 32.46cm x 58.42cm (12.778” x 23”) | 35.56cm x 50.8cm (14″ × 20″) | 34.47cm x 48.26cm (13.571” x 19” ) |
| Medium | 60.96cm x 101.6cm (24″ × 40″) | 55.03cm x 99.06cm (21.667” x 39”) | 60.96cm x 86.36cm (24″ × 34″) | 59.87cm x 83.82cm (23.571” x 33”) |
| Large | 111.76cm x 152.4cm (43.6″ × 60″) | 83.26cm x 149.86cm (32.778” x 59”) | 111.76cm x 152.4cm (43.6″ × 60″) | 107.04cm x 149.86cm (42.143” x 59”) |
| X-Large | 111.76cm x 187.96cm (43.6″ × 74″) | 103.01cm x 185.42cm (40.556” x 73”) | 111.76cm x 162.56cm (43.6″ × 64″) | 110.74cm x 160.02cm (43.6” x 63”) |
Color LVT Film Chart Sizes
| 5 x 7 Squares Multi-Chart Dimensions | 5 x 9 Squares Multi-Chart Dimensions | Medium Dimensions (5 x 7 Squares Only) |
Small Dimensions (5 x 7 Squares Only) |
||||
|---|---|---|---|---|---|---|---|
| Active Area | Bar-to-Bar Height |
Active Area | Bar-to-Bar Height |
Active Area | Bar-to-Bar Height |
Active Area | Bar-to-Bar Height |
| 197mm × 136mm (7.75″ × 5.357″) |
128mm (5.208″) |
235mm × 131mm (9.25″ × 5.139″) |
122.8mm (4.834″) |
229mm × 163.2mm (9.016″ × 6.425″) |
153.5mm (6.043″) |
160mm × 114.3mm (6.3″ × 4.5″) |
107.5mm (4.23″) |
| 102mm × 70mm (4″ × 2.765″) |
66.1mm (2.601″) |
102mm × 56mm (4″ × 2.222″) |
53.1mm (2.090″) |
||||
| 64mm × 44mm (2.5″ × 1.728″) |
41.3mm (1.625″) |
76mm × 42mm (3″ × 1.667″) |
39.8mm (1.568″) |
||||
| 51mm × 35mm (2″ × 1.328″) |
33mm (1.3″) |
51mm × 28mm (2″ × 1.111″) |
26.5mm (1.045″) |
||||
| 38mm × 26mm (1.5″ × 1.027″) |
24.8mm (0.975″) |
38mm × 21mm (1.5″ × 0.833″) |
19.9mm (0.784″) |
||||
Black & White Film Chart Sizes
This 5 x 9 squares chart has an active chart area of 48.3cm x 26.81cm (19″ x 10.56″) in a total film size of 30.48cm x 50.8cm (12″ x 20″). Bar-to-bar height is 252mm (9.92″). An optional color film patch can be applied to this target.
Color Chart Options
Inclusion of the color chart enables testing of color accuracy. If the color option is selected, the “focus star” pattern that aides in focusing is replaced by a 20 patch color chart.
Pre-Distortion Options
Pre-distorted charts offer the ability to map the outer edges of a wide angle or fisheye lens using SFRplus. These distortion levels are available
| Level | Matrix (5 x 7 squares) | Matrix (5 x 9 squares) |
|---|---|---|
| No distortion | [0 0] | [0 0] |
| Distort | [0.833 1.123] | [0.833 1.375] |
| Distort+ | [1.167 1.577] | [1.167 1.982] |
| Ultradistort | [1.333 2.313] | [1.333 2.958] |
We do not recommend using semi-gloss paper for wide angle lenses or pre-distorted charts.
Custom variations of the SFRplus chart are available. Please contact sales@imatest.com to discuss your specific requirements.
Documentation and software support
SFRplus can be run either through the highly-interactive Rescharts interface or as a batch-capable fixed module. The key documentation for getting started is Using SFRplus Part 1, found in the SFRplus section of the Documentation page. We recommend framing the chart with a small amount of white space above and below the top and bottom bars. Badly-framed charts can be analyzed with SFR using manual ROI selection.
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