51 lines
1.5 KiB
Go
51 lines
1.5 KiB
Go
package images4
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const (
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// Icon parameters.
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// Image resolution of the icon is very small
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// (11x11 pixels), therefore original image details
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// are lost in downsampling, except when source images
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// have very low resolution (e.g. favicons or simple
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// logos). This is useful from the privacy perspective
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// if you are to use generated icons in a large searchable
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// database.
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IconSize = 11 // Exported to be used in package imagehash.
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// Resampling rate defines how much information
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// (how many pixels) from the source image are used
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// to generate an icon. Too few will produce worse
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// comparisons. Too many will consume too much compute.
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samples = 12
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// Similarity parameters.
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// Cutoff value for color distance.
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colorDiff = 50
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// Cutoff coefficient for Euclidean distance (squared).
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euclCoeff = 0.2
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// Coefficient of sensitivity for Cb/Cr channels vs Y.
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chanCoeff = 2
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// Similarity thresholds.
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// Euclidean distance threshold (squared) for Y-channel.
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thY = float64(IconSize*IconSize) * float64(colorDiff*colorDiff) * euclCoeff
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// Euclidean distance threshold (squared) for Cb and Cr channels.
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thCbCr = thY * chanCoeff
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// Proportion similarity threshold (5%).
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thProp = 0.05
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// Auxiliary constants.
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numPix = IconSize * IconSize
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largeIconSize = IconSize*2 + 1
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resizedImgSize = largeIconSize * samples
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invSamplePixels2 = 1 / float64(samples*samples)
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oneNinth = 1 / float64(9)
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one255th = 1 / float64(255)
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one255th2 = one255th * one255th
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sq255 = 255 * 255
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maxUint16 = 65535
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)
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