Chapter Four Objectives Understand role of resolution in representation of detail Show how digital images and details are sharpened and enhanced

Proper Sharpness and Detail Represents sharp focus Supports image’s details Avoids evident digital artifacts

Digital color specialists are concerned about pixel resolution When the image is captured When the image is edited When the image is output

Sharpness and Detail In digital images, proper sharpness and detail are dependant on Pixel resolution Software sharpening filters

Pixels Pixel resolution is expressed as PPI, or pixels per inch The higher the PPI, the more detail can be represented

Pixel Creation Total pixel count Pixel resolution of resulting image Dictated by CCD or CMOS chip, “film” of a digital camera Pixel resolution of resulting image Controlled by distribution of captured pixels

A scanner’s optics and software set the pixel resolution of an image when it is digitized

The number of captured pixels squeezed into a square inch controls the size of individual pixels and dimensions of entire image

File Compression Reduces a file’s size for storage or transmission

Resampling Two forms Not recommended as it adversely affects image detail

Resampling Reduce an image’s height and width dimensions and throw out pixels in the process Enlarge an image and create new pixels in the process

Anti-Aliasing Blurs edges along curves and diagonals to reduce the apparent “stair-stepping” effect of square pixels representing non-square features

UnSharp Mask Software sharpening filters “trick” the eye into believing that there is more detail in the image than there really is

Edge Definition and Grain The Unsharp Mask filter enhances edge definition and smoothes non-edge (or grain) areas. The defined edge created where the black and ivory regions of the scanner casing touch, and where the aqua and ivory regions touch will both respond to USM adjustments.

Edge Definition and Grain An edge is any border created where light and dark regions touch, or differently colored regions touch. The defined edge created where the black and ivory regions of the scanner casing touch, and where the aqua and ivory regions touch will both respond to USM adjustments.

Advanced Sharpening Techniques Sharpening individual channels or selected areas allows a greater degree of sharpening control

Advanced Sharpening Techniques The Smart Sharpen Filter in Photoshop CS2 confers the ability to split edges for enhanced control