Understanding a few basics on the nature of the HVC space, and how to operate within it, will help you a great deal with using this program and making color selection decisions altogether. In the overview page, you saw that just like with other color spaces in Photoshop's color picker, you can choose which axis to control when viewing HVC slices, by clicking the radio buttons next to the HVC boxes, shown here.

And that the three configurations give you access to the types of HVC slices shown below.

These diagrams show for each setting, what qualities are indicated by the horizontal and vertical directions. Notice the variation in the shape of the color space. For instance, when looking at a hue slice, the peak (maximum chroma) generally occurs in the middle (mid value). Whereas the top and bottom (white and black) are always at 0% chroma.

The variation in shape is due to the fact that not every hue at every value level will have a fully saturated chroma level. The hue peaks are as saturated as a color can be for that hue (and even then, not many peaks are even near 100% chroma). The less saturated colors progess on an interesting contour, according to their true visual properties, until reaching white and black.

This is part of the true power of the HVC space. Geometric simplicity is sacrificed for visual accuracy. Every color's position in the space is dictated by its precise visual properties.

But this means it's possible to select outside the boundaries of HVC. Notice below, how a position that is valid in one hue, may not be valid in another.

When the hue was changed, the boundary receded, but the value and chroma (vertical and horizontal) position of the selected color remained the same. The result is an invalid HVC (which defaults to white). To select the nearest in-bounds color, click the HVC Out-of-Gamut Flag. The flag appears whenever you select a color outside the HVC gamut.

Split Slider

As an added convenience, the color picker features a "split slider". On the left side of the slider is an unchanging gradation, showinf you the general range of the active axis (hue, value, etc). On the right side is a gradation showing the range for that axis (e.g.), given the current position of the other two (e.g. value and chroma). So the right side depends on the selected color, and changes as you pick new colors. It also shows positions on the axis where the colors are outside the HVC bounds.

Other Color Spaces

All the other color spaces standard to Photoshop are included: HSB, RGB, Lab, and CMYK. Active these the same way you active HVC for selection: click one of the radio buttons next to the space and particular axis you want to view. The other spaces benefit from the split slider as well. And just as with the standard color picker, if you select a color using one space, the numbers for that color in the other color space text boxes are automatically shown.

View the next topic: 3. Measuring contrast

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