Our color database

Our unique color database displays color transformation data taken from different cameras at the exact same conditions. We use two type of color charts for our database, the GretagMacBeth ColorChecker 24 is used for most of the plots and the GretagMacBeth ColorChecker DC is only used for our gamut plot.

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Our entire system is based on the D65 color temperature, as D65 is being used by both sRGB and Adobe RGB color profiles. GretagMacBeth ColorChecker charts are photographed with all color transformations available by the camera (i.e. Standard, landscape…). The captured data (JPEG file) is then analyzed and converted into the LAB color space. The final data is uploaded to our color database to be presented in several plots.

Accuracy of comparison

Exposure is the key to produce accurate color. We always try to match the ideal exposure as much as possible. However, even with all the parameters (lighting, shutter, aperture and ISO) being relatively the same, some cameras are less or more sensitive than others. That being said, our largest margin of error is 0.11EV.
—- In order to limit the margin of error we take 3 shots of every frame and analyze the data.

Lab Plot

Our LAB plot gives you a way to compare, observe and understand how two cameras transform the SAME color in the the final image.

It is important to understand that camera makers DO NOT wish to reproduce exactly real world colors into the final image (that is true regarding the photographer also..) . Most of the camera makes have developed a color model based on the “memory color” concept and a world wide research of culture color preferences (the same can be said about films of course)

The LAB plot is simply a map of colors made by the camera in the device independent LAB space. The horizontal axis represents a* and the vertical axis represents b* of the LAB color space. a* and b* data values from the camera are mapped into the plot and marked as a circle for EACH of the GretagMacBeth ColorChecker 24 patches.

When a second camera profile is selected the data is mapped and marked by X and a line is drown between the two camera profiles selected.

By doing so, you could understand how two cameras profile treat the SAME color.

If you would like to map also the GretagMacBeth ColorChecker 24 reference values on the map, simply check the “show ColorChecker 24 reference values in LAB plot” box. The new data will be mapped as squares.

By doing so, you can understand the color transformation that has been made by the camera maker from real world color to the image.

Delta C

Delta C presents the chromatic differences between two colors in a form of a number. Delta C of 0 means there is no difference in color. Delta C of 2-3 or under, indicates that there is a small difference in color that is hardly seen by the eye. Larger Delta C values could be very noticeable to the eye.

For your comfort we’ve marked the Delta C values with color. Green is for values under Delta C 5, Blue is for values above Delta C 5 but under 10 and Red is for values above Delta C 10.

We calculate Delta C with a very simple equation:

Delta C = ( (a2 – a1)^2 + (b2 – b1)^2 )square root

Please note that this equation does not take into account the fact that differences in some colors are more sensitive by the eye than differences in other colors. However, when dealing with large differences such as in digital cameras these differences will be very apparent.

Visual Differences

The ‘Visual Differences’ plot allows you to actually see the colors a camera has produced. The colors are presented in the ColorChecker 24 format and each patch contains color from all sources. By default, you will be shown the color from both profiles you’ve selected and the actual GretagMacBeth ColorChecker 24 real world colors.

By checking out “Show ColorChecker 24 reference values in other plots” box at the top of the page you can hide GretagMacBeth ColorChecker 24 real world colors.
If an Adobe RGB profile was selected, values will be shown as Adobe RGB values! your browser probably can’t display this profile correctly. To convert Adobe RGB values into sRGB values, check the “Convert Adobe RGB into sRGB” at the top of the page.

Gamut

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Our gamut plot presents the most broad RGB points we could capture on Yyx plot. Please note that the results are a bit misleading. A camera gamut is theoretically depended on the sensor’s color filters and the sensor itself. The best way to test how much from the primary color a camera is capable to capture is by taking a picture of a very saturated and pure primary colors. Unfortunately, this is not something easy to have in hand.

Our gamut plot is based on the much less pure and saturated Red, Green and Blue patches of the GretagMacBeth ColorChecker DC chart. And so the three Yxy points shown on the gamut plot are NOT the best a camera can do. They are simply show how the three patches were converted by the camera profile selected. Because those three patches are quite pure and saturated, you can still understand how pure primary color would be transformed by a certain color profile.

Gamma

Our Gamma plot is simply showing the 6 monochromatic patches of the ColorChecker 24 next to the real world GretagMacBeth ColorChecker 24 values. Please note that 6 patches are not sufficient to fully describe gamma in a detailed manner. Further more, as the whitest white and the blackest black of the chart are not challenging for the camera, dynamic range could not be tested here. (You can check our dynamic range tests here)

The Gamma plot is a good way to understand what kind of ‘Luma curve’ a color profile of a camera produces against a different one.

Back to the color database