To adjust brightness curves 1 Select one paint object to adjust. The paint object can be in edit mode. You can select an area in the image. If you don’t make a selection, the entire image is affected. 2 Choose Image > Adjust > Curves. 3 In the Channel pop-up menu, select the composite channel or an individual channel to adjust. To adjust multiple channels, select the channels in the Channels palette first. 4 To change the shape of the existing curve, make sure the curve button at the bottom-left is selected. •   Click points that you want to keep the same •   Drag points on the curve that you want to change. Or, enter values in the Input and Output boxes. For example, to keep midtones the same, click the center of the curve, then drag other areas of the curve. To adjust midtones without affect- Curves dialog box The graph shows how Canvas maps input brightness values to output values. Select Pre- view to see the effect on the image. A Choose a channel to adjust. B The grayscale ramp shows the lightness scale, either 0-255 (dark to light) or 0-100 percent (light to dark). Click the ramp to reverse the scale and the curve. C    Type brightness values in the Input and Output boxes. Or, drag the pointer (circled) to specify brightness values. Here, pixels of 157 brightness are lightened to 171. D    Click this icon and drag a point on the curve to reshape the curve. Click the curve to add up to 19 control points. Drag points off the curve to delete them. E To draw a disconnected segment, click this icon and drag in the graph. F With the pencil (E) selected, click to smooth the curve. C Input A B F D   E Tip To redraw the curve complete- ly, or to create sharp changes in brightness for a tonal range, click the pencil and draw a new curve or segment.
Canvas 8 Help: Image adjustment and correction (10 of 24)                                           Page #692