Cropping, transformations and a control work

A photograph often catches unwanted things or the subject slides toward the edge of the frame; we fix this with the Crop tool, key C: dragging from one corner of the picture to the opposite one frames the chosen part, the frame's markers change its size, dragging outside a corner rotates it, and Enter confirms. The options bar lets you choose the aspect ratio (1:1, 4:5, 16:9) and whether to delete or keep the cropped pixels. If the shooting point is wrong, the vertical edges of a building lean toward each other at the top; we correct this with Perspective Crop or Edit → Transform → Perspective: we move the top corners until the vertical lines of the grid are parallel to the building wall. The transformations are in Edit → Transform: Scale, Rotate, Skew, Distort, Perspective, Warp, rotation by 180° and 90°, and Flip Horizontal/Vertical; free transform is Ctrl+T. In newer versions the proportions are kept automatically while resizing and Shift switches this off. Before applying an operation, the part of the picture must be selected. In an enlarged raster no new detail appears: the program “invents” extra pixels by interpolation, so quality drops.