Light photon equalization and its application to X-ray film digitization.
The principle of light photon equalization (LPE) is to modulate the light source during X-ray film digitization so that the dynamic range of the transmitted light into a photo-detector can be precisely controlled to obtain improved signal-to-noise ratio (SNR). The modulation of the light source is derived from a smoothed image of the original digitized image. The final output digital image is reconstructed by convoluting the modulation function with the resultant LPE image. The LPE was implemented in a laser film digitizer as a prototype. The results shows that, although the dynamic range of X-ray films is about 10(4):1, the range of the transmission light into a photo detector was reduced to 10(2):1 with this technique. Also the SNR improved by a maximum factor of five in the lung area of a digitized chest radiograph.
Ishimitsu
Y
Y
Konica Corporation, Imaging Systems Division, Tokyo, Japan.
Huang
H K
HK
D000465:Algorithms; D003626:Data Display; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007834:Lasers; D008027:Light; D008168:Lung / Q000000981:diagnostic imaging; D008482:Mediastinum / Q000000981:diagnostic imaging; D017785:Photons; D011856:Radiographic Image Enhancement / Q000295:instrumentation / Q000379:methods*; D013902:Radiography, Thoracic; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D014962:X-Ray Film