Test Patterns

The Test Patterns sub-menu under Transformations/Special Effects lets you create various images useful for testing and other specialized purposes.

Checkerboard…

This transformation lets you create checkerboard patterns with your choice of colors for the squares and optionally with lines separating the squares. Such patterns can be cropped and used as masks or printed and used as lens distortion targets.

Number of Columns -- The number of columns of squares

Number of Rows -- The number of rows of squares

Cell Size -- The size of each square (in pixels)

Line Width -- The width of lines between squares (set to zero for no lines)

Color 1 -- Color in upper left corner

Color 2 -- Alternate color

Line Color -- Color of the lines separating squares

Resolution (dpi) -- Image resolution in dots per inch

Color Chart…

This transformation creates an image the contains a wide range of colors based on the HSV color space. This is a useful printer test image since it contains the full gamut of colors.

In the vertical direction, the V channel varies in 12 even steps from the bottom of the chart towards the top. The bottom row corresponding to V = 0% is omitted as this would be entirely black.

In the horizontal direction, the H channel varies in 18 even steps with the last column being a repeat of the first column.

Within each square, the S channel varies in 6 even steps with zero at the center and 100% at the edges.

Color Wheel…

This transformation creates an image of the color wheel containing all combinations of HSV hue and saturation with V held at 100%. This is another useful printer test image. You can select the Image Width (in pixels) and Background Color as well as selecting 8-bit or 16-bit output.

Cosine Falloff…

This transformation creates a black and white image that is white in the center and whose brightness falls off as the cosine of the angle from a viewer directly above the center of the image to any given pixel in the image. The Field of View slider lets you set the diagonal field of view in degrees – the wider the field of view, the more rapid the falloff. This transformation models the way vignetting occurs in wide angle lenses and can be used to create masks to apply or remove vignetting.

Image Width -- Width of the image in pixels

Image Height -- Height of the image in pixels

Resolution (dpi) -- Image resolution in dots per inch

Field of View -- Diagonal field of view in degrees

Gamma Test…

This transformation creates black and white image with a gray square in the center. The image must be viewed at a zoom factor of 1:1 to work, and due to resampling, the illustration above may not accurately represent what you will see. As you adjust the gamma slider, the central square gets lighter or darker -- when it matches the background, the gamma value is approximately equal to your current monitor gamma. For most WIndows computers, this should be around 2.2, although computers set up for commercial prepress applications are often set to gamma 1.8 instead. This transformation just does a rough check of monitor gamma -- for more accurate results, use a monitor calibrator.

Hue Saturation Chart…

This transformation creates an image that contains a range of colors based on the HSV color space with V fixed at 100%. This is a useful printer test image since it contains the full gamut of colors.

Resolution Chart…

This transformation creates an image containing a set of resolution test patterns useful for testing printers and monitors. To be useful, it needs to be viewed or printed at 1:1 as it tests the resolution of a device at the pixel level.

This image lets you compare the performance of different printers and evaluate their ability to reproduce fine detail. The test file consists of a series of different patterns. The left-hand part of the target consists of three rows of test patterns – the features in the first row are 1 pixel wide, the features in the second row are 2 pixels wide and the features in the third row are 3 pixels wide. Each row consists of 5 columns – horizontal lines, vertical lines, checkerboard, isolated black pixels on a white background, and isolated white pixels on a black background. The right-hand side of the test target is a grayscale rendition of a 2-dimensional sine function of increasing frequency – this simply means the light and dark circles get closer and closer together the further you get from the lower left corner.

Printing the target

The target size is 810 x 310 pixels and is designed to be printed 1:1 at the printer resolution, i.e. so that one image pixel corresponds to one printer dot.

Evaluating the results

The top row of the test target lets you see how well your printer can reproduce detail at the individual pixel level. Most printers do not reproduce any of these patterns very well, but some do better than others. Most printers will behave differently for vertical and horizontal lines and this indicates that one or the other direction has higher resolution. The lines and checkerboards should be rendered consistently across the entire pattern. The isolated pixel patterns let you see how single pixels are rendered. Often black on white will show up much better than white on black due to dot overlap. This is normal but some printers fare better than others. The middle and bottom rows of patterns should be rendered much better than the top row. Finally, you can also get an overall idea of the printer's resolving power by counting how many rings you can resolve in the 2D sine pattern in different directions. A microscope or powerful magnifier can be helpful when examining the printout.

Using the image to evaluate monitor resolution is similar, but the image must be viewed at a zoom factor of 1:1 to each image pixel corresponds to a screen pixel.

Hue Saturation Chart

This transformation creates an image the contains a range of colors based on the HSV color space with V fixed at 100%. Hue varies horizontally and Saturation varies vertically. This is a useful printer test image since it contains the full gamut of colors.

Sharpen Test

This transformation creates an image you can use to evaluate the effects of various sharpening settings. It consists of a series of vertical gradient strips of various widths superimposed on a horizontal gradient background. This means that the image contains areas where more or less every gray level is adjacent to more or less every other gray level. When sharpened, this test image can reveal artifacts that occur based on how distinct the edges are.

Simulated Q-13

This transformation creates simulated version of the Kodak Q-13 test target. The original target is printed on heavy paper and has a series of 20 gray patches that vary in density from 0.0 to 1.90 in steps of 0.10. If you print out this simulated Q-13 on a printer that achieves roughly this density range you should get a close reproduction of the original chart. The printed chart can be used in conjunction with the Match Reference transformation to perform neutral balancing.

Step Wedge…

This transformation creates step wedge image that is extremely useful for calibrating all sorts of black and white workflows.

Image Type -- Output image type (either 8-bit or 16-bit black and white)

Labels -- Determines if or how the patches are labeled.

Text Size -- Label text size

Orientation -- Horizontal or Vertical – determines if the patches are stacked vertically or horizontally.

Pixel Values -- Ascending or Descending – sets the patch order (light to dark or dark to light)

Total Number of Patches -- Total number of patches in the image – the last row or column may not be full.

Patches per Row/Column -- The number of patches in each row (if orientation is horizontal) or the number of patches in each column (if orientation is vertical).

Patch Width -- Patch width in pixels

Patch Height -- Patch height in pixels

Patch Spacing -- Gap between patches in pixels - the gap is filled with alternating black and white pixels to make it easier to see patch boundaries if the patches are nearly the same brightness

Resolution (dpi) -- Resolution in dots per inch