Digital Conversion of SingleUse Camera Ranging Lab Michael

Digital Conversion of Single-Use Camera Ranging Lab Michael Spaeth SUC Tech Center Eastman Kodak Company

Ranging Lab

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 Ag. X negative

Digital Method - Theory • Digitally sample images – Whether with CCD array or film scanner • Run images through a slanted-edge test to find MTF • Compare MTF’s to find ‘best’ focus

Slanted-Edge Algorithm • Slanted-Edge software www. pima. net/standards/iso/tc 42/wg 18__sfr_matlab_page. htm • Written in Matlab • Needs high contrast in target • Needed to be converted to IDL

Slanted-Edge Test - Matlab

IDL Conversion Test

Ranging Lab Program • Loops Slanted-Edge Analysis • Compares MTF values to determine ‘best’ focus

Ranging Lab Program Demo

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

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