In the greymap box, you can shift individual or multiple shades up or down to make them lighter or darker. You can modify brightness and contrast, create a negative image, and posterize by modifying the greymap directly. To achieve these effects easily and see how they affect the line of shades represented on the greymap, see the procedures that follow this one. Then you can return to this procedure and modify the greymap directly to fine-tune your effects.

NOTE: Shifting an individual shade will not change the picture if the picture doesn't use that corresponding shade of grey.

1. Select the cropping tool from the tool bar, and then select the picture whose image you want to fine-tune.

2. Choose Image Control from the Edit menu.

3. Position the pointer in the greymap, and click or drag to redefine the shades of grey. Wherever you click or drag shifts each corresponding shade of grey (normally in the diagonal line) to the new position on the greymap.

4. Click Apply to see the results. Make further changes, or undo all changes by clicking Normal. Clicking Cancel or the close box will undo any changes made since you chose the Image Control command.

5. Click OK when you're done.
   To zoom in so you can easily work with the dots that represent individual shades, click the Zoom up arrow as many as four times to magnify the dots. Click the Zoom down arrow to zoom out.

When you have zoomed in and want to go to another part of the greymap, position the pointer over the greymap box and hold down the Option key. The pointer changes to the hand tool that lets you drag the greymap to a new position.