RESUMEN
A fast computer-generated phase-only hologram (POH) calculation is needed to realize a holographic display. Existing iterative methods require many iterations and thus require speed improvement, and noniterative methods add constraints to the image, resulting in restrictions on quality or range of expression. In this paper, we propose an efficient iteration algorithm without using a feedback process. For the several initial iterations among the entire iteration process, the image constraint was replaced by a histogram adjusted image. This pre-iteration can compensate for the loss of bright and dark pixels in the image reconstructed by the POH, resulting in a more accurate POH. The quality of image reconstructed by the proposed method was compared with that of existing algorithms by computer simulation and optical regeneration. Compared to the previous method, a 1.17dB increase in peak signal-to-noise ratio was obtained, and the number of iterations to achieve the same image quality has been reduced by 23%. The proposed method hardly increased the amount of computation and could be used simultaneously with the existing feedback methods.
RESUMEN
[Purpose] This study was conducted to quantify the effect of sling exercise therapy in the recovery of lumbosacral sagittal alignment (LSA) and in the control of low back pain. [Subjects and Methods] A total of 102 chronic low back pain patients were divided into two groups, a physical therapy group and a sling exercise group. In both groups, programs were conducted thrice a week for twelve weeks. With respect to LSA, pelvic tilt (PT), sacral slope (SS), and pelvic incidence (PI) were measured with plain radiography. Pain was measured on a visual analogue scale (VAS). [Results] Differences were found in visual analogue scale, delta score of visual analogue scale, pelvic tilt, delta score of pelvic tilt, and delta score of pelvic incidence between sling exercise therapy and physical therapy groups. VAS, pelvic tilt, and pelvic incidence was positively changed after sling exercise. However, only the visual analogue scale was found to be improved after physical therapy. [Conclusion] Sling exercise therapy and physical therapy were effective in reducing pain. However, pelvic tilt and pelvic incidence were positively changed after sling exercise therapy for Lumbosacral Sagittal Alignment, but were unchanged after physical therapy. Therefore, sling exercise therapy is more effective than physical therapy for the recovery of Lumbosacral Sagittal Alignment in patients with chronic low back pain.