A - Brightness/Contrast

The Brightness/Contrast adjustment lets you make simple adjustments to the tonal range of an image. Moving the brightness slider to the right increases tonal values and expands image highlights, to the left decreases values and expands shadows. The contrast slider expands or shrinks the overall range of tonal values in the image.

B - Levels

You use the Levels adjustment to correct the tonal range and color balance of an image by adjusting intensity levels of image shadows, midtones, and highlights. The Levels histogram is a visual guide for adjusting the image key tones.

C - Curves

You can use Curves or Levels to adjust the entire tonal range of an image. The Curves adjustment lets you adjust points throughout the tonal range of an image (from shadows to highlights). Levels have only three adjustments (white point, black point, gamma). You can also use Curves to make precise adjustments to individual color channels in an image.

D - Exposure

Adjusts the highlight end of the tonal scale with minimal effect in the extreme shadows. In the Adjustments Panel, the second row of buttons is used primarily for color balancing images.

E - Vibrance

Vibrance adjusts the saturation so that clipping is minimized as colors approach full saturation. This adjustment increases the saturation of less-saturated colors more than the colors that are already saturated. Vibrance also prevents skin tones from becoming over-saturated.

F - Hue/Saturation

Hue/Saturation lets you adjust the hue, saturation, and lightness of a specific range of colors in an image or simultaneously adjust all the colors in an image. This adjustment is especially good for fine-tuning colors in a CMYK image so that they are in the gamut of an output device.

G - Color Balance

The Color Balance command changes the overall mixture of colors in an image for generalized color correction. Color casts can easily be removed by moving the slider to the opposite color to neutralize the unwanted tone. The tonal change can be targeted to the lightest part of the image (highlights), the darkest tones (shadows) or the overall image (midtones).

H - Black & White

The Black & White adjustment lets you convert a color image to grayscale while maintaining full control over how individual colors are converted. You can also tint the grayscale by applying a color tone to the image, for example to create a sepia effect. Black & White functions like the Channel Mixer, which also converts color images to monochrome while allowing you to adjust color channel input.

I - Photo Filter

The Photo Filter adjustment mimics the technique of placing a colored filter in front of the camera lens to adjust the color balance and color temperature of the light transmitted through the lens and exposing the film. Photo Filter also lets you choose a color preset to apply a hue adjustment to an image. If you want to apply a custom color adjustment, the Photo Filter adjustment lets you specify a color using the Adobe Color Picker.

J - Channel Mixer

Using the Channel Mixer adjustment, you can create high-quality grayscale, sepia tone, or other tinted images. You can also make creative color adjustments to an image. The Channel Mixer adjustment options modify a targeted (output) color channel using a mix of the existing (source) color channels in the image. Color channels are grayscale images representing the tonal values of the color components in an image (RGB or CMYK). When you use the Channel Mixer, you are adding or subtracting grayscale data from a source channel to the targeted channel.

K - Color Lookup

The new Color Lookup Adjustment Layer in Photoshop CS 6 has several options (3DLUT File, Abstract, and Device Link) that are used to load different “looks”. These looks are achieved by remapping every color in the image to a different one using a lookup table (LUT). I think that many photographers and designers will find their resulting color shifts quite interesting. You can think of these tables as a sort of meta-adjustment, a way to apply pre-packaged adjustments (sometimes lots of adjustments together) in one step.

L - Invert

The Invert adjustment inverts the colors in an image - making a negative of the positive image or vice-versa.

M - Posterize

The Posterize adjustment lets you specify the number of tonal levels (or brightness values) for each channel in an image and then maps pixels to the closest matching level. For example, choosing two tonal levels in an RGB image gives six colors: two for red, two for green, and two for blue.

N - Threshold

The Threshold adjustment converts grayscale or color images to high-contrast, black-and-white images. You can specify a certain level as a threshold. All pixels lighter than the threshold are converted to white; all pixels darker are converted to black.

O - Selective Color

Selective color correction is a technique used by high-end scanners and separation programs to change the amount of process colors in each of the primary color components in an image. You can modify the amount of a process color in any primary color selectively— without affecting the other primary colors. For example, you can use selective color correction to dramatically decrease the cyan in the green component of an image while leaving the cyan in the blue component unaltered.

P - Gradient Map

The Gradient Map adjustment maps the equivalent grayscale range of an image to the colors of a specified gradient fill. If you specify a two-color gradient fill, for example, shadows in the image are mapped to one of the endpoint colors of the gradient fill, highlights are mapped to the other endpoint color, and midtones are mapped to the gradations in between.

You can adjust the Clone Stamp Tool the same way as the Brush and Eraser Tools — just adjust its values at the top of the application window.

With the Clone Stamp Tool selected, hover your cursor over the area of your image that you wish to repeat. Hold down the ALT key (OPTION on a Mac) and click on the image. The cursor will change shape and will appear as a target symbol.

Then, move your cursor to the new area of your image where you wish to duplicate the original portion of the image. Click and “paint” with your cursor; the portion of your image that you originally sampled will appear in the new area of your image.

The Clone Stamp Tool takes a bit of practice to master, but it’s useful once you become comfortable with it. You can use it to create multiple images of a single product within the same frame, or to remove blemishes or spots on a product’s surface.

To use the Healing Brush Tool, hover your cursor over the area of your image that you want to sample. Hold down the ALT key (OPTION on Mac) and click on the sample area (the cursor will become a target symbol when you hold down ALT/OPTION).

Move your cursor to the area of the image that you want to blend your sample into. Click and hold your mouse to “paint” with your cursor in the new area of your image. The Healing Brush Tool will sample the original portion of your image and paint it over the new area of your image, blending the pixels together.

Like the Clone Stamp Tool, you’ll need some patience to become a pro with the Healing Brush Tool. But it could be a better option than the Clone Stamp Tool to remove spots or blemishes from a product image, depending on the image and what you need to do to it.