Tone curve and histogram

Close button

Color-histogram button

Channel list box

Freehand curve button

Smooth curve button

Tone curve

White, gray, and black-point buttons

Point-value button

Apply button

Histogram

Input shadow/gamma/highlight text boxes

Input shadow/gamma/highlight sliders

Output shadow/highlight text boxes

Output shadow/highlight sliders

Reset button

Click the auto-setting button to maximize contrast and color balance automatically. The change is reflected in the prescan image.

Scanner Notes

When cursor is placed over the image, the RGB display and tone curve show the value of that point. The point is indicated by a circle on the tone curve.

Click the tone-curve and histogram button in the image-correction tab.

Click the arrow next to the channel list box to select the channel. To make adjustments to the color balance of the image, select the appropriate color channel. To adjust the contrast or brightness of the image, select the RGB chan- nel.

Place the mouse pointer over the tone curve. Click and drag the curve.

Each time the tone curve is clicked, a new node is attached. The nodes can be moved by clicking and dragging. The input and output levels of the node are displayed as it is moved. The input level (horizontal axis) refers to the original image, and the output level (vertical axis) refers to the correction applied to the image.

Any changes made on the tone curve are immediately applied to the displayed image.

To draw a tone curve, click the freehand-curve button. The mouse pointer changes to the pencil tool when placed in the tone-curve box.

Click and drag to draw a new curve. Extreme image manipulations are possible with the free- hand curve tool.

To smooth a rough freehand curve, click the smooth-curve button. Nodes are automatically placed on the curve and can be adjusted with the mouse.

With extreme freehand curves, the smooth curve button may significantly change the shape of the curve. The reset button cancels all changes in all channels.

The histogram indicates the distribution of pixels with specific brightness and color values in the displayed image. The histogram can maximize the output of the image data. Changes made with the histogram are also displayed on the tone curve.

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Advanced image processing

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