Photoshop

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Document setup

Resolution

Resolution is how many pixels there are per square inch of your image.

  • In digital images, you do not know how many inches wide or tall any given image will appear on someone else's computer... every computer display has its own resolution settings which you do not control, especially over the web. So resolution settings are not important for digital work, however, many people set the resolution to 72 pixels per inch for some strange reason. This confusion is referred to as the '72 dpi myth'.
  • In printed images, any given printer will have a specific number of dots it can print per inch, so resolution is important. The printer's resolution determines the resolution setting to use in Photoshop... usually this is at least 300 pixels per inch.

Color systems

Photoshop allows you to talk about color with several different systems, including:

  • RGB (Red, Green, and Blue) - an additive color system
  • CMYK (Cyan, Magenta, Yellow, and BlacK/Key) - a subtractive color system
  • Lab (Lightness, a, and b)
  • HSB (Hue, Saturation, and Brightness)

More information on color systems:

Selections

  • Almost everything in Photoshop depends upon your skill making selections.
  • Selections allow you to indicate which part of a given layer you want to manipulate.
  • There are several tools used to make selections: the Marquee tools (Rectangular, Elliptical, etc), the Lasso tools, the Quick Select and Magic Wand tools.
  • There is also the Select->Color Range menu option.
  • The Select menu also has various options you can use to tweak selections.

Adjustment layers

  • adjustment layers can allow you to shift the color or tone in pixels
  • to create an adjustment layer, click on the “black and white cookie” icon at the bottom of the Layers panel, and select your preferred adjustment type.
  • adjustment layers by default alter the color in all layers below them in the layers panel. If you want to apply adjustments to only a single layer, hover between the adjustment layer and the layer directly below it in the Layers panel, hold down the alt/option key and click to make the adjustment layer only apply to the layer directly below it.

Layer masks

  • layer masks allow you to control the transparency (also known as the alpha channel) in every pixel in a given layer.
  • do not erase or cut any data from photos or any layers you use as source material in a composite image… use layer masks instead to make parts of a layer transparent rather than deleting/cutting those pixels
  • to create a layer mask, click the layer mask icon at the bottom of the Layers panel. This will add a new icon next to the layer icon in the Layers panel… in order to make any changes to the layer mask, this second icon must be clicked/highlighted.
  • If you have made a selection prior to clicking to make a layer mask, clicking to make a layer mask will automatically use your selection for the mask… this can be handy.
  • paint white into a layer mask to make the pixels in that area opaque… paint black to make the pixels transparent… paint gray to make the pixels partially transparent/opaque.

Free Transform

  • Free Transform allows you to change the width, height, rotation, and skew of any selection
  • to rotate, initiate a Free Transform, hold the cursor outside of the Transform box. You will see the cursor change to a rotation icon. Click and drag to rotate.
  • To resize a selection, click and drag on the anchor boxes that appear at the corners of the transform box
  • Changing the proportions of a selection as you resize it is usually a fatal mistake that makes your image look amateurish. To make sure you maintain proportions when resizing a selection with the Free Transform, hold down the Shift key while resizing
  • to complete any Free Transform operation, hit the Enter key

Clone stamp

  • the Clone Stamp tool allows you to paint one part of the image into another area of the image as if you were using a brush and ink
  • to use it, make sure you have selected the layer you want to copy from in the Layers panel. Click on the Clone Stamp tool. Hold down alt/option and click on the area of the image you want to copy from. Then, in a new layer, click and drag to paint that area into a new part of the image.


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