Selection method for mark of Chinese character eyesight test chart

Abstract

The invention relates to a selection method for visual targets of a Chinese character eye chart. The method comprises the following steps of: carrying out spatial frequency component analysis after converting Chinese characters into picture formats, then working out a mean of the frequency spectrum energy of spatial frequencies, adopting cluster analysis to cluster images of Chinese characters, selecting a group of Chinese characters similar with the mean of the frequency spectrum energy, and selecting Chinese characters which simultaneously have horizontal strokes, vertical strokes, slant strokes and curved strokes from the group of Chinese characters as the visual targets of the Chinese character eye chart. Besides giving consideration to the factors of stroke number, character frequency, character form, etc., the selection method for the visual targets of the Chinese character eye chart also selects the Chinese characters similar with the mean of the frequency spectrum energy of spatial frequencies as the visual targets through carrying out the spatial frequency component analysis of Chinese character images, thereby meeting the universal laws of a human visual system on Chinese character recognition and identification in a better way. The Chinese character eye chart made from the Chinese character visual targets selected through the method can more correctly detect the threshold value of the font size of Chinese characters read by a testee.

Description

technical field [0001] The invention relates to a method for selecting an optotype of a Chinese-character visual acuity chart. Background technique [0002] The eye chart is one of the most important tools in ophthalmology diagnosis. Through the measurement of visual acuity, on the one hand, we can understand the health status of the eyes, and on the other hand, we can understand the examinee's ability to distinguish the daily reading text. At present, in ophthalmology clinical visual acuity examination, there are illiterate E, letter and number etc. as the visual mark of visual acuity chart. In many countries where English is the first language, the British Standard Alphabet and Sloan letters and numbers are commonly used. In China, the visual acuity chart with illiterate E as the visual standard is the most widely used in clinical visual acuity testing. The basic principles of these optotype designs are consistent: each stroke accounts for 1 / 5 of the height of the entir...

AI Technical Summary

Problems solved by technology

However, the processed Chinese characters are completely different from the Chinese characters in daily reading materials, so there is inevitably a deviation between the test results and the actual visual acuity

The other type uses the number of strokes, frequency of characters, shape and other factors as the main reference factors for visibility. However, according to relevant research, even Chinese characters with the same number of strokes do not necessarily have the same visual stimulation to the visual system.

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