66 lines
2.1 KiB
Go
66 lines
2.1 KiB
Go
package images4
|
|
|
|
// Threshold multiplication coefficients for func CustomSimilar.
|
|
// When all values equal 1.0 func CustomSimilar is equivalent
|
|
// to func Similar. By setting those values less than 1, similarity
|
|
// comparison becomes stricter (more precise). Values larger than 1
|
|
// will generalize more and show more false positives. When uncertain,
|
|
// setting all coefficients to 1.0 is the safe starting point.
|
|
type CustomCoefficients struct {
|
|
Y float64 // Luma (grayscale information).
|
|
Cb float64 // Chrominance b (color information).
|
|
Cr float64 // Chrominance r (color information).
|
|
Prop float64 // Proportion tolerance (how similar are image borders).
|
|
}
|
|
|
|
// CustomSimilar is like Similar, except it allows changing default
|
|
// thresholds by multiplying them. The practically useful range of
|
|
// the coefficients is [0, 1.0), but can be equal or larger than 1
|
|
// if necessary. All coefficients set to 0 correspond to identical images,
|
|
// for example an image file copy. All coefficients equal to 1 make func
|
|
// CustomSimilar equivalent to func Similar.
|
|
func CustomSimilar(iconA, iconB IconT, coeff *CustomCoefficients) bool {
|
|
|
|
if !customPropSimilar(iconA, iconB, coeff) {
|
|
return false
|
|
}
|
|
if !customEucSimilar(iconA, iconB, coeff) {
|
|
return false
|
|
}
|
|
return true
|
|
}
|
|
|
|
func customPropSimilar(iconA, iconB IconT, coeff *CustomCoefficients) bool {
|
|
return PropMetric(iconA, iconB) <= thProp*coeff.Prop
|
|
}
|
|
|
|
func customEucSimilar(iconA, iconB IconT, coeff *CustomCoefficients) bool {
|
|
|
|
m1, m2, m3 := EucMetric(iconA, iconB)
|
|
|
|
return m1 <= thY*coeff.Y &&
|
|
m2 <= thCbCr*coeff.Cb &&
|
|
m3 <= thCbCr*coeff.Cr
|
|
}
|
|
|
|
// Similar90270 works like Similar, but also considers rotations of ±90°.
|
|
// Those are rotations users might reasonably often do.
|
|
func CustomSimilar90270(iconA, iconB IconT, coeff *CustomCoefficients) bool {
|
|
|
|
if CustomSimilar(iconA, iconB, coeff) {
|
|
return true
|
|
}
|
|
|
|
// iconB rotated 90 degrees.
|
|
if CustomSimilar(iconA, Rotate90(iconB), coeff) {
|
|
return true
|
|
}
|
|
|
|
// As if iconB was rotated 270 degrees.
|
|
if CustomSimilar(Rotate90(iconA), iconB, coeff) {
|
|
return true
|
|
}
|
|
|
|
return false
|
|
}
|