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FOCUSSING SLIDE 32pt 20pt

FOCUSSING SLIDE 32pt 20pt. CAMERA Sensor Processing within Camera. Types of sensor CCD CMOS. SENSORS. e.g. MINOLTA DIMAGE A1 Typical size 8.8 x 6.6mm Max. 2560 x 1920 pixels = 5 million Pixel size and quality are important, not just number of pixels. BAYER SENSOR.

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FOCUSSING SLIDE 32pt 20pt

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  1. FOCUSSING SLIDE 32pt 20pt

  2. CAMERA • Sensor • Processing within Camera

  3. Types of sensor • CCD • CMOS SENSORS e.g. MINOLTA DIMAGE A1 Typical size 8.8 x 6.6mm Max. 2560 x 1920 pixels = 5 million Pixel size and quality are important, not just number of pixels

  4. BAYER SENSOR Each pixel records strength of only 1 colour

  5. DEMOSAICINGProcessing within camera to‘estimate’ the strength of the other colours for each pixel • Nearest pixel • Interpolation • Other more sophisticated methods

  6. CAMERA USER CHOICES • Adjustments before clicking shutter: • White balance • Vivid colours • Special scenes - portraits, beach, night Compression Pixel size TIFF 2560 x 1920 XFIN 2080 x 1560 FINE 1600 x 1200 STD 640 x 480

  7. OUTPUT FORMAT 8 bits for each colour, indicating strength of each. [“24 bit image”] RED I I I I I I I I GREEN I I I I I I I I BLUE I I I I I I I I Total number of colours 256x256x256= 16,777,216

  8. ANOTHER OUTPUT FORMAT • RAW format • Unprocessed in camera • - not even demosaiced • 12 to 14 bits/pixel. Available only at 2560 x 1920 • Requires special processing software • - supplied with camera • - otherwise e.g. Raw Therapee • Also contains EXIF data (Exposure, date, etc)

  9. 35mm film FOVEON SENSOR No demosaicing required

  10. OPERATIONS IN COMPUTER (a) Artistic - colour temperature, colour balance, brightness, contrast, sharpness, remove lamppost, etc, etc (b) File size - reducing the bit depth

  11. CHANGING BIT DEPTH Palleted Images I I I I I I I I 8 bits/pixel pointing to any of 256 palette colours

  12. FACTORS AFFECTING PALETTING (1) How to construct the palette (a) Optimised Median Cut - based upon frequency of colours in image. Not accurate (b) Optimised Octree - more accurate (2) How to reduce number of colours (a) Nearest colour - gives high contrast (b) Error diffusion - takes account of adjacent colours (c) Dithering can give illusion of more colours

  13. Showing Pixels

  14. DISCUSSION TOPICS • Is it better to set white balance, contrast etc in camera, or to do it in computer? - or even to use a Raw file? • Any experience of matching monitor image with printed image?

  15. POSSIBLE FUTURE TOPICS • Artistic processing in computer - enhancement • Colour theory • Printing techniques - getting colours right • Pros and cons of various software

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