The Colorimetric Calculator


Conversion flow
Input specifications
Technical specifications


ColorConverter is an app that converts among most color modes as well as providing correlate and daylight color temperature and a chromaticity diagram. ColorConverter works on iPad with iOS 5.0 or better.

On first startup, the app displays a number of empty text fields and few buttons:


Initially all fields are empty, which means that all values are undetermined. Note that an empty field does not indicate 0 (zero); it indicates instead that the value of the field is undetermined. The app provide a placeholder that appears in each field when the field is empty.

To become familiar with the calculator, tap the button Random (bottom right). Each time you tap this button the app loads a random color (see screenshot below). In this example the random color is the Adobe RGB color in the green rectangle. From the RGB number all others color modes are calculated: HSB, HSL, Hexadecimal, XYZ, Yxy, etc.


To enter values, tap a field to display the keyboard. You can keep the keyboard open until all data have been entered. You can also change your mind and tap on a field of a different mode when the keyboard is open.

Enter a source color into the corrisponding fields, for example .7 into X field, .6 into Y field and .8 into Z field.


Then tap on the Go button of the keyboard and all other modes are calculated. You will get this:


The source color X = 0.7, Y = 0.6, Z = 0.8 is convert to Y = 0.6, x = 0.33, y = 0.286, and to RGB, HSB, HSL, Lab and all other modes.

The start mode is indicated by a green rectangle. A point in the chromaticity diagram and a colored swatch may be display, if the calculation get a "real" color (here above is a pink color) else an empty square is displayed (see the first screenshot above). Since many colors are out of the screen gamut, the color of the swatch is only approximate. For the in-gamut colors, it is assumed that the screen is sRGB.

ColorConverter includes two groups of color modes. The first group (here below on the left) includes a series of color modes (RGB, HSB, etc) to consider under the RGB space illuminant (Adobe RGB D65 in the example here below). The second group (here below on the right) includes another series of color modes to consider under the illuminant indicated (D75 in the example). Colors are converted between a RGB illuminant and a reference illuminant using different chromatic adaptation transforms (CAT, Scaling here below).


With the buttons on the top of the screen you can select a RGB color space (and related illuminant), a reference illuminant and a CAT type (if first illuminant is different from second illuminant).

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ColorConverte is a project by Mauro Boscarol. For information and requests, send an email to me.