Professionals : what's the contract in adobe photoshop ?

It makes the selection gets smaller by a specific amount eg.1 pixel

• In the toolbar, hold down the Spot Healing Brush  and select the Patch tool .

• In the options bar, do the following:

  Content-Aware Patch options

  Patch

  Choose Content-Aware to select the content-aware option.

  Adaptation

  Choose a value for how closely the patch reflects the existing image patterns.

  Sample All Layers

  Enable this option to create the result of the move in another layer using information from all layers. Select the target layer in the Layers panel.

   

• Select an area to replace on the image. You can use the Patch tool to draw a selection, or use any of the other Selection tools as well.

• Drag the selection over the area you want to generate a fill from.