Which processing step maps input pixel values to output to adjust image brightness and contrast?

Which processing step maps input pixel values to output to adjust image brightness and contrast?

• A. Edge enhancement
• B. Automatic brightness control
• C. Lookup table (LUT)
• D. Histogram analysis

Answer: (C)

Understanding how a lookup table remaps pixel values to change brightness and contrast. A LUT stores a mapping from every possible input gray level to a new output level. By changing this table, you directly determine how bright each pixel will appear and how the tonal range is distributed, effectively brightening or darkening the image and increasing or decreasing contrast. In digital radiography, window level and width are implemented as a specific LUT curve, so adjusting windowing changes the LUT and thus the displayed image tones. Edge enhancement uses spatial filtering to sharpen boundaries, not the overall gray-scale mapping. Automatic brightness control adjusts brightness through algorithms or exposure-related adjustments rather than a direct pixel-value remap. Histogram analysis examines the distribution of gray levels to guide adjustments but does not perform the pixel-value remapping itself.

Understanding how a lookup table remaps pixel values to change brightness and contrast. A LUT stores a mapping from every possible input gray level to a new output level. By changing this table, you directly determine how bright each pixel will appear and how the tonal range is distributed, effectively brightening or darkening the image and increasing or decreasing contrast. In digital radiography, window level and width are implemented as a specific LUT curve, so adjusting windowing changes the LUT and thus the displayed image tones.

Edge enhancement uses spatial filtering to sharpen boundaries, not the overall gray-scale mapping. Automatic brightness control adjusts brightness through algorithms or exposure-related adjustments rather than a direct pixel-value remap. Histogram analysis examines the distribution of gray levels to guide adjustments but does not perform the pixel-value remapping itself.