Digital Conversion of SingleUse Camera Ranging Lab

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Digital Conversion of Single-Use Camera Ranging
Lab

• Michael Spaeth
• SUC Tech Center
• Eastman Kodak Company

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Ranging Lab
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Problems with Ranging Lab

• Negatives are read via microscope
• Tiring for observer
• Human differences
• What you see as a line pair, I may not
• Red tint of color AgX negative

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Digital Method - Theory

• Digitally sample images
• Whether with CCD array or film scanner
• Run images through a slanted-edge test to find
  MTF
• Compare MTFs to find best focus

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Slanted-Edge Algorithm

• Slanted-Edge software
• www.pima.net/standards/iso/tc42/wg18/wg18__sfr_mat
  lab_page.htm
• Written in Matlab
• Needs high contrast in target
• Needed to be converted to IDL

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Slanted-Edge Test - Matlab
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IDL Conversion Test
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Ranging Lab Program

• Loops Slanted-Edge Analysis
• Compares MTF values to determine best focus

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Ranging Lab Program Demo
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Problems With Method

• Inconsistant
• Does not return same value each time through
• Possible Reason
• low contrast in images, creating high error in
  MTF calculation
• Possible Solution
• use target with higher contrast
• alter image to raise contrast

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Problems With Method

• All the plots are the same
• Possible Reason
• multiple systems influencing system MTF
• Possible Solutions
• Analyze all systems other than optics and
  subtract MTF for these systems
• Reduce number of systems in process