Adjusting the curves to an image will affect its colour values, thus the overall colour of an image.
- Check that the image is active in the Layers Palette.
- Select the Pipette Tool from the Tools Palette.
- Go to Window Menu > Info.
- Go to Edit Menu > Gamma. The Gamma Window will open. The information displayed in the window may vary from this example depending on which buttons are selected in the top left of the window.
With an RGB image, the Gamma Window will be split into Red, Green and Blue sections. These sections represent the individual channel colours that are combined to create an RGB image. They can be adjusted separately in order to change the colour values of the image.
With a CMYK image the window will be split into cyan, magenta, yellow and black sections.
With N-Channel images, the window will be split into the number of channels contained with the n-channel profile used to separate the image.
Ensure Preview is checked in the bottom left of the Gamma Window. This will make sure any adjustments made to any of the curves will be shown in real time in the Design Window, so you can view the changes before making them permanent.
- Click on the design with the Pipette Tool to select a colour. You will see the R, G and B colour density readings appear in the Info Window.
In the Gamma Window a vertical line will appear in each of the Red, Green and Blue panes. These lines indicate the colour make – up of the image. Clicking on different parts of the image with the Pipette Tool in the Design Window will change the readings and will show the lines at different positions within each pane. It will also change the readings in the Info Window.
When the Gamma Window is first opened, each curve is shown as a diagonal line stretching at a 45° angle between 0% and 100%.
- Edit one of the curves by clicking on the diagonal line at any point. Push it up or down to change the colours in the image. You can add as many points along the line as you wish.
Note: There is a setting in the General Settings which restricts the ability of adding nodes to a curve in the Gamma Window unless ⇧ (shift key) is held down. The purpose of this is to aid precise and accurate adjustments as it removes the likelihood of accidentally adding nodes to the curve. If you want to make tiny precise adjustments to the curve we suggest you switch this setting on by ticking Shift Click to Add Gamma Nodes. If you would prefer to add nodes without having to hold down ⇧ (shift key), untick this setting.
When working with an image, editing any of the Red, Green or Blue curves will adjust the colour balance of the image. For example you can reduce the amount of red in the image by pulling the red curve down. Try experimenting with the curves to see the different effects you can achieve.
- When you are happy with the appearance of the image, click on Do Gamma at the bottom of the window to apply the changes.
The curves will reset to their default diagonal lines but the window will remain open, allowing you to make more adjustments if you need to.