{'fraction_non_alphanumeric': 0.026867275658248254, 'fraction_numerical': 0.009134873723804407, 'mean_word_length': 5.487804878048781, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Quantifying the image-sticking phenomenon for the checkerboard stimuli: contrast, spatial frequency, edge effect, and noise interference

This study aimed to determine the relationship between the image-sticking phenomenon and human visual perception. The contrast sensitivity of various checkerboard patterns was measured over a wide range of spatial frequencies. Four subjective tests were designed to determine the contrast threshold of spatial frequency, edge effect, and noise interference for the checkerboard stimuli. The experimental results were divided into four parts: (1) Special frequency: the contrast sensitivity remains on 45 dB (dB = 20 log10 (1/contrast)) steadily in low-spatial frequency. The contrast sensitivity dropped drastically when the spatial frequency was increased from 0.5 to 1.3(log C/deg). The spatial frequency 0.5 (log C/deg) had maximum contrast sensitivity (2) Edge effect: the original checkerboard pattern was filtered by convolution with the different mean filter sizes to produce a variety of scale blurred edges, and to estimate the influence of the edge effect as regards human perception. The results showed that sharper edges of checkerboard stimuli can affect the contrast threshold (3) Gaussian noise: checkerboard stimuli add noise with Gaussian distribution to evaluate the addition of the noise effect for checkerboard stimuli. The low-contrast checkerboard stimuli were affect that when σ becomes greater and the level of contrast sensitivity drops (4) Simultaneous edge effect and Gaussian noise interference: the level of contrast sensitivity is lower than the others and the curve of contrast sensitivity is similar to that of Gaussian noise. According to the experimental result the contribution of the spatial frequency, edge effect, and noise interference for human visual perception could be determined.