A 
APPLICATIONS OF WHITE-LIGHT OPTICAL DENSITY ENCODING TECHNIQUE IN MEDICINE 
HU Ruiming, YANG Sugin 
College of Technology 
University of Hainan 
570001 Haikou, China 
Commission V 
ABSTRACT 
This paper will briefly outline the principle and approaches of the Optical Density 
Encoding Technique. The main advantages of this technique will be emphasized.The 
results of the medical applications of this technique, such as: False-coloring of 
black and white imagery taken through Optical Microscope, Ultrasonoscope type B, 
Transmissive Electronical Microscope ( TEM ), Scanning Electronical Microscope 
(SEM), and Computerized Tomograph ( C T ) are reported. 
KEY WORDS: Image Analysis, Image Interpretation, Image Processing. Optical, 
Superimposition. 
1. INTRODUCTION 
This paper is a sister paper of the Optical Density 
Encoding Techniques [1]. It is mainly devoted to the 
medical applications. We are not going to present 
the basic principle and approaches here again. We 
will just give an outline of them in section 2. The 
advantages of this technique are: 
1) High sensitivity for distinguishing faint 
density differences in a black and white 
imagery by different false-colors; 
2) Ability of 2-D parallel processing: 
3) Huge capacity of information; 
4) Low price of the equipment; 
5) Easy operation. 
The main advantages of this technique are that it 
can distinguish faint density differences in the 
order of magnitude of wave length and the cost for 
establishing such a device is quite low, because the 
optical interference and diffraction principles have 
been applied in this technology. If there are some 
imagery which are difficult for processing with 
other methods in order to be able to distinguish the 
targets required, the technique introduced may solve 
your problems. 
2. BASIC PRINCIPLE AND APPROACHES 
These will be outlined in steps. The main points of 
this technology are: 
1) Superimposing the Ronchi  Orating to the 
original black and white imagery for making 
this Grating modulated or encoded by the 
original imagery; 
2) Bleaching this encoded imagery for getting a 
Transparent Phase Grating; 
3) Decoding it through filtering in a white-light 
information processing equipment. A saturated, 
bright, and abundant false-color image will be 
obtained. 
During decoding in the white-light information 
processing equipment each wave length in the white 
280 
light will be diffracted and interfered to get the 
image with each wave length, and the images with 
different wave lengths will be superimposed to get 
the false-color imagery. When filtering we can 
interrupt the other orders of the diffraction 
spectrum and only let the zero order or the first 
order to pass through in order to get the false- 
color imagery. 
The colors in, the  false-color imagery are 
complementary for the zero order and the first 
order. For the best use of the light energy, we 
usually only choose Lower orders. 
In addition, in £he white-light information 
processing equipment, the 4f system is uasually 
used. In order to get the enlarged false-color 
pictures directly, we have designed a white-light 
ZOOM processor ( WLZP ) [1] which can adjust the 
enlargement of the false-color images easily, and 
the length of the room used can be reduced 
accordingly. By the way, all of our false-color 
images were obtained by this WLZP. 
3. REPORT ON MEDICAL APPLICATIONS 
In medical applications the imagery of the specimens 
used in different instruments are usually with 
single wave length ( e.g. black and white ). It does 
not like the MSS Landsat Data with multiple spectrum 
bands. Therefore, the false-color imagery can only 
be produced by a single black and white imagery. The 
Optical Density Encoding Technique is one of the 
methods for false-coloring of the black and white 
imagery. In this paper we will only show the results 
in medical applications. We have processed 7 samples 
with single wave length ( black and white ) imagery 
through 5 different instruments in different 
applications. 
3.1 False-coloring of a TEM Imagery 
This imagery is offered by the Central Laboratory in 
the Academy of Medical Science of Hubei Province, 
Wuhan, China. The Target was a small white mouse's 
kidney cell. After false-coloring we have got the 
following results: 
3.1.1 The colors of two kinds of the Chromatins in 
this cell are completely different and are 
easy to be distinguished; 
3.1.2 Each membrane of the Chondriosome in the