Study On The Color Characterization Of Digital Camera In General Office Lighting Environment

With the internet technology getting popularization rapidly in daily life, digitalcamera not only has become a kind of electronic products for public consumption, butalso, as a major image acquisition tool, is widely used in graphic image, colormanagement, computer vision, aerospace, and e-commerce, playing a very importantrole. The color space of camera is device dependent. Furthermore their spectralrespond do not directly correspond to the device independent color matching functionbased on the CIE standard colorimetric observer. The camera could not failthfulreproduction the color of scene. The color device characterization is such animportance device dependent way to improve the color accurate on captured images.Characterizing color image device is a vital method of improving the colorreproduction quality of an image. This paper adopts the commonly-used method ofpolynomial regression model, on the basis of detailed study about the characterizationof digital camera in the condition of light box lighting, puts forward and studies themethods and achievable accuracy of digital camera characterization in general officelighting environment. This paper has also shed light on one method of colorreproduction from digital camera to monitor. Specific works are as follows:(1) The first step is studying the characterization of digital camera in standardlight box lighting environment. The accuracy of characterization is only14.0CIELAB color difference units, which is low. Through the experiment, the main reasonsthat influence the accuracy of characterization have been found, namely, theinhomogeneous illuminance of light source and the differences of material swatch.(2) The second step is studying the color characterization of digital camera in thegeneral office lighting environment of “natural light” lighting in the daytime and the“fluorescent lamp” lighting at night. The author puts forward the method of digitalcamera characterization in daytime natural light office lighting environment withoutusing any specialized equipment, only using the color card with X-rite ColorChecker24colors, compares its characterization accuracy with that of using specializedequipment in characterization in two lighting office environment of natural lighting in the daytime and fluorescent lamp lighting at night. The characterization accuracyreaches3.63CMC(1:1)chromatic aberration units, reaching the level of application.(3) The third step is the studying of color reproduction from digital camera tomonitor. The author presents a simple way of color reproduction from digital camerato monitor. Taking the24color lumps of X-rite ColorChecker putted in the D65light box as testing sample, the author uses the camera to get its RGB value, and usesPR715to measure its CIE XYZ value, by applying the monitor-defaulted PALcharacteristic equation, works out the corresponding R G B of the attained XYZ，thenthrough establishing the three channels relationship of camera RGB and monitorR G B, works out the reproduced R’G’B’ image of the RGB of any image shot by thecamera on the monitor. The average chromatic aberration of objective assessmentdeclines from17.1to12.5CMC(1:1) color difference units. The subjectiveassessment shows that this method has improved the quality of color reproduction.