Symmetry values differ based on the color of the image about imagefluency HOT 1 CLOSED

# load image
img_red <- imagefluency::img_read("img_red.png") # change accordingly

# vertical symmetry (left vs right)
img <- OpenImageR::RGB_to_HSV(img_red)[,,1] # keep only HUE
# OpenImageR::imageShow(img)

imgW <- dim(img)[2] # image width
stimL <- img[, 1:floor(imgW / 2)] # left image half
stimR <- img[, imgW:(1 + ceiling(imgW / 2))] # right image half (flipped!)

# vectorize matrices
pixL <- as.vector(stimL)
pixR <- as.vector(stimR)

# estimate percentage of pixels being identical
mean(pixL == pixR)

# -- Note: if you want to allow for a little bit of noise in the image,
#          define a noise threshold and compare the pixel differences against
#          this threshold
noise = .01
mean(abs(pixL - pixR) < noise)


# horizontal symmetry (top vs bottom)
# -- Note: here, we just rotate the image by 90 degrees, thereby allowing to
#          remain the rest of the code the same
img = OpenImageR::RGB_to_HSV(imagefluency::rotate90(img_red))[,,1] # keep only HUE

imgW <- dim(img)[2]
stimL <- img[, 1:floor(imgW / 2)]
stimR <- img[, imgW:(1 + ceiling(imgW / 2))]

pixL <- as.vector(stimL)
pixR <- as.vector(stimR)

mean(pixL == pixR)