A. Green B. Yellow C. Red D. Magenta E. Blue F. Cyan
Because there are numerous ways to achieve similar results in colour balance, it's useful to consider the type of image you have and the effect you want to produce. If you're new to adjusting colour components, it helps to keep a diagram of the colour wheel on hand. You can use the colour wheel to predict how a change in one colour component affects other colours and also how changes translate between RGB and CMYK colour models.
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For example, you can decrease the amount of any colour in an image by increasing
the amount of its opposite on the colour wheel - and vice versa. Similarly,
you can increase and decrease a colour by adjusting the two adjacent colours
on the wheel, or even by adjusting the two colours adjacent to its opposite.
In a CMYK image, you can decrease magenta either by decreasing the amount of magenta or its proportion (by adding cyan and yellow). You can even combine these two corrections, minimising their effect on overall lightness. In an RGB image, you can decrease magenta by removing red and blue or by adding green. All of these adjustments result in an overall colour balance containing less magenta. |
The Hue/Saturation command lets you adjust the hue, saturation, and lightness of the entire image or of individual colour components in an image. Adjusting the hue, or colour, represents a move around the colour wheel. Adjusting the saturation, or purity of the colour, represents a move across its radius.
A. Saturation B. Hue C. Brightness D. All hues
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You can also use the colourise option to add colour to a grey scale image
converted to RGB, or to an RGB image - for example, to make it look like a
duotone by reducing its colour values to one hue. To use the Hue/Saturation command: 1 Open the Hue/Saturation dialogue box. (See Making colour adjustments.) The two colour bars in the dialogue box represent the colours in their order on the colour wheel. The upper colour bar shows the colour before the adjustment; the lower bar shows how the adjustment affects all of the hues at full saturation. 2 For Edit, choose which colours to adjust: Choose Master to adjust all colours at once. Choose one of the other pre-set colour ranges listed for the colour you want to adjust. An adjustment slider appears between the colour bars, which you can use to edit any range of hues. (For information on how to modify the slider's range, see the instructions following this procedure.) 3 For Hue, enter a value or drag the slider until the colours appear as you want. The values displayed in the text box reflect the number of degrees of rotation around the wheel from the pixel's original colour. A positive value indicates clockwise rotation, a negative value counter clockwise rotation. Values can range from -180 to +180. 4 For Saturation, enter a value or drag the slider to the right to increase the saturation or to the left to decrease it. The colour shifts away from or toward the centre of the wheel, relative to the beginning colour values of the selected pixels. Values can range from -100 to +100. 5 For Lightness, enter a value or drag the slider to the right to increase the lightness or to the left to decrease it. Values can range from -100 to +100. 6 Click OK. |
1 Choose an individual colour from the Edit menu in the dialogue box.
2 Do any of the following to the adjustment slider:
Drag one of the white triangles to adjust the amount of colour fall - off without affecting the range.
Drag one of the light grey bars to adjust the range without affecting the amount of fall - off.
Drag the dark grey centre part to move the entire adjustment slider, selecting a different colour area.
Drag one of the vertical white bars next to the dark grey centre part to adjust the range of the colour component. Increasing the range decreases the fall - off, and vice versa.
Ctrl-drag (Windows) or Command-drag (Mac OS) the colour bar so that a different colour is in the centre of the bar.
A. Adjusts fall - off without affecting range B. Adjusts range without affecting fall - off C. Moves entire slider D. Adjusts range of colour component
If you modify the adjustment slider so that it falls into a different colour range, the name changes to reflect this. For example, if you choose Yellow and alter its range so that it falls in the red part of the colour bar, the name changes to Red 2. You can convert up to six of the individual colour ranges to varieties of the same colour range (for example, Red through Red 6).
Note: By default, the range of colour selected when you choose a colour component is 30° wide, with 30° of fall - off on either side. Setting the fall - off too low can produce banding in the image.
3 To edit the range by choosing colours from the image, select the eyedropper tool () in the dialogue box and click in the image. Use the eyedropper + tool to add to the range; use the eyedropper - tool to subtract from the range.
While the eyedropper tool is selected, you can also press Shift to add to the range or Alt (Windows) or Option (Mac OS) to subtract from it.
1 (Photoshop) If you are colorising a grey scale image, choose Image > Mode > RGB to convert the image to RGB.
2 Open the Hue/Saturation dialogue box. (See Making colour adjustments.)
3 Select colourize. The image is converted to the hue of the current foreground colour, if the foreground colour is not black or white. The lightness value of each pixel does not change.
4 Use the Hue slider to select a new colour if desired. Use the Saturation and Lightness sliders to adjust the saturation and lightness of the pixels.
5 Click OK.To Page 7
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