CTS Charts

These are the original source images that were used to produce the paper charts for CTS-1 thru CTS-6. The first 3 were produced with Adobe Photoshop as vector objects, allowing precise selection of shapes and colors. CTS-2 and 6 were made in 8-bit RGB mode using the sRGB color space. CTS-1 and 3 were made in 8-bit CMYK Color Mode. Each image is sized to print on 8x10 paper with the 2 internal boxes sized at a 4x6 aspect ratio for capture by cameras. The 4-frame film strips were taken of color 8x10 prints on a copy-stand with adjustable GVM 560-AS CRI-97 LED lights set to a color temperature of 60K. 

The prints captured on the film strips reflect the colors after the printing process converts “pure” RGB or CMY colors to the CMYK mode used by printers. There is NO attempt made to suggest the colors on any of the CTS charts are “true” RGB or CMY colors. For example, the Cyan block on CTS-1 was created in Photoshop as “pure” Cyan set at 100-0-0-0 in the CMYK mode. However, when looking at the DSLR scan of that paper chart in Photoshop, the Cyan block shows 88-2-27-0-0 in the CMYK model. Very few (if any) printer can print “pure” color but will use a combination of inks to produce the best match possible to the referenced color.

CTS-1: The CTS-1 frame shows some resolution targets and the six primary screen/print color blocks (RGB and CMY). The upper left target is shown at 100% black, 50% black and 18% neutral gray.  The resolution targets show line pairs from 5 pixels to 2 pixels wide when scaled for an 8x10" print.  The color blocks (Red/Green/Blue and Cyan/Magenta/Yellow) were originally set in Photoshop with CMY blocks set to pure CMY colors and the RGB blocks set to their matching CMYK equivalents. Cyan is 100-0-0-0 and it’s complement Red is 0-100-100-0.

CTS-2: The CTS-2 frame is a set of sample color blocks that can be used like an IT8 target. The RGB values below the block show the RGB values as created in PhotoShop. The RGB values inside the block show an average RGB value of after printing and captured as with a DSLR scan. Blocks 1 to 4 are representative values of average skin tones. Block 5 is set to blank Kodak Portra 400 film base. Blocks 6 to 15 are sample colors selected from the Photoshop color schemas. Blocks 16 to 20 are white, 18% gray, 50% gray, 75% gray, and black.

CTS-3: The CTS-3 frame shows a color wheel and gradients to provide a reference sample of the wider color spectrum with gradual changes between the primary colors. The source image is set in CMYK mode in the sRGB color space. The right side of the image shows primary and secondary colors as they transition to the next color in the color wheel. This chart provides an excellent target for reviewing how hue/white balance adjustments affect various colors and gradients.

CTS-6: The CTS-6 frame provides a test box set with common everyday items that can be used to color balance the image. CTS-6 is a frame from a printed digital image. This chart provides real world items and colors as they appear on the same print paper and captured with the same lighting/setup as the first 3 color charts. The original source image was taken of the test box in indirect mid-day sunlight with a DSLR. This chart allows quick comparisons after negative conversion and white balancing and the effects while trying to “fix” a specific color.

The film images were captured with a Nikon N80 camera with a Nikon Micro Nikkor 60mm f2.8G ED lens. The digital images were captured with a Nikon D5500 24MP DX camera and the same lens. For both sets, the aperture was set at f5.6 with an auto-exposure setting for speed adjustment.

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