qGBbBShift - Emerging Trends in Image Processing, Computer Vision, and Pattern Recognition - page 139

that the ρGBbBShift method gets the beter results both in PSNR (objective image quality) and
C w PSNR (subjective image quality) in contrast to MaxShift and GBbBShift methods.
FIGURE 5 Comparison among MaxShift (Blue Function), GBbBShift (Green Function) and
ρGBbBShift (Red Function) methods applied to H i -SET coder. 512 × 512 pixel Image 1600
with (a-b) 8 and (c-d) 24 bpp are employed for this experiment. ROI is a patch at the center of
the image, whose size is 1/16 of the image. The overall image quality of decoded images at
different bits per pixel is contrasted both (a and c) objectively and (b and d) subjectively. (a)
PSNR grayscale. (b) CwPSNR grayscale. (c) PSNR color. (d) CwPSNR color.
When MaxShift method applied to JPEG2000 coder and ρGBbBShift applied to H i -SET
coder are compared, in the whole image quality assessment of image 1600 , JPEG2000 obtains
better objective quality both for grayscale and color images ( Figure 6(a) and (c) , respectively).
But when the subjective quality is estimated ρGBbBShift coded images are perceptually beter.
FIGURE 6 Comparison between MaxShift method applied to JPEG2000 coder and
rGBbBShift applied to Hi-SET coder. 512 x 512 pixel Image 1600 with (a-b) 8 and (c-d) 24 bits
per pixel are employed for this experiment. ROI is a patch at the center of the image, whose
size is 1/16 of the image. The overall image quality of decoded images at different bits per
pixel are contrasted both (a and c) objectively and (b and d) subjectively.
A visual example is depicted by Figure 7 , where it can be shown that there is no perceptual
diference between ROI areas besides the perceptual image quality at BG is beter when
ρGBbBShift is applied to the H i -SET coder ( Figure 7(d) ) . Furthermore, Figure 7(b) and (c)