pySaliencyMap.py

#-------------------------------------------------------------------------------
# Name:        pySaliencyMap
# Purpose:     Extracting a saliency map from a single still image
#
# Author:      Akisato Kimura <akisato@ieee.org>
#
# Created:     April 24, 2014
# Copyright:   (c) Akisato Kimura 2014-
# Licence:     All rights reserved
#-------------------------------------------------------------------------------

import cv2
import numpy as np
import pySaliencyMapDefs

class pySaliencyMap:
    # initialization
    def __init__(self, width, height):
        self.width  = width
        self.height = height
        self.prev_frame = None
        self.GaborKernel0   = np.array(pySaliencyMapDefs.GaborKernel_0)
        self.GaborKernel45  = np.array(pySaliencyMapDefs.GaborKernel_45)
        self.GaborKernel90  = np.array(pySaliencyMapDefs.GaborKernel_90)
        self.GaborKernel135 = np.array(pySaliencyMapDefs.GaborKernel_135)

    # extracting color channels
    def SMExtractRGBI(self, inputImage):
        # convert scale of array elements
        src = np.float32(inputImage) * 1./255
        # split
        (B, G, R) = cv2.split(src)
        # extract an intensity image
        I = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY)
        # return
        return R, G, B, I

    # feature maps
    ## constructing a Gaussian pyramid
    def FMCreateGaussianPyr(self, src):
        dst = list()
        dst.append(src)
        for i in range(1,9):
            nowdst = cv2.pyrDown(dst[i-1])
            dst.append(nowdst)
        return dst
    ## taking center-surround differences
    def FMCenterSurroundDiff(self, GaussianMaps):
        dst = list()
        for s in range(2,5):
            now_size = GaussianMaps[s].shape
            now_size = (now_size[1], now_size[0])  ## (width, height)
            tmp = cv2.resize(GaussianMaps[s+3], now_size, interpolation=cv2.INTER_LINEAR)
            nowdst = cv2.absdiff(GaussianMaps[s], tmp)
            dst.append(nowdst)
            tmp = cv2.resize(GaussianMaps[s+4], now_size, interpolation=cv2.INTER_LINEAR)
            nowdst = cv2.absdiff(GaussianMaps[s], tmp)
            dst.append(nowdst)
        return dst
    ## constructing a Gaussian pyramid + taking center-surround differences
    def FMGaussianPyrCSD(self, src):
        GaussianMaps = self.FMCreateGaussianPyr(src)
        dst = self.FMCenterSurroundDiff(GaussianMaps)
        return dst
    ## intensity feature maps
    def IFMGetFM(self, I):
        return self.FMGaussianPyrCSD(I)
    ## color feature maps
    def CFMGetFM(self, R, G, B):
        # max(R,G,B)
        tmp1 = cv2.max(R, G)
        RGBMax = cv2.max(B, tmp1)
        RGBMax[RGBMax <= 0] = 0.0001    # prevent dividing by 0
        # min(R,G)
        RGMin = cv2.min(R, G)
        # RG = (R-G)/max(R,G,B)
        RG = (R - G) / RGBMax
        # BY = (B-min(R,G)/max(R,G,B)
        BY = (B - RGMin) / RGBMax
        # clamp nagative values to 0
        RG[RG < 0] = 0
        BY[BY < 0] = 0
        # obtain feature maps in the same way as intensity
        RGFM = self.FMGaussianPyrCSD(RG)
        BYFM = self.FMGaussianPyrCSD(BY)
        # return
        return RGFM, BYFM
    ## orientation feature maps
    def OFMGetFM(self, src):
        # creating a Gaussian pyramid
        GaussianI = self.FMCreateGaussianPyr(src)
        # convoluting a Gabor filter with an intensity image to extract oriemtation features
        GaborOutput0   = [ np.empty((1,1)), np.empty((1,1)) ]  # dummy data: any kinds of np.array()s are OK
        GaborOutput45  = [ np.empty((1,1)), np.empty((1,1)) ]
        GaborOutput90  = [ np.empty((1,1)), np.empty((1,1)) ]
        GaborOutput135 = [ np.empty((1,1)), np.empty((1,1)) ]
        for j in range(2,9):
            GaborOutput0.append(   cv2.filter2D(GaussianI[j], cv2.CV_32F, self.GaborKernel0) )
            GaborOutput45.append(  cv2.filter2D(GaussianI[j], cv2.CV_32F, self.GaborKernel45) )
            GaborOutput90.append(  cv2.filter2D(GaussianI[j], cv2.CV_32F, self.GaborKernel90) )
            GaborOutput135.append( cv2.filter2D(GaussianI[j], cv2.CV_32F, self.GaborKernel135) )
        # calculating center-surround differences for every oriantation
        CSD0   = self.FMCenterSurroundDiff(GaborOutput0)
        CSD45  = self.FMCenterSurroundDiff(GaborOutput45)
        CSD90  = self.FMCenterSurroundDiff(GaborOutput90)
        CSD135 = self.FMCenterSurroundDiff(GaborOutput135)
        # concatenate
        dst = list(CSD0)
        dst.extend(CSD45)
        dst.extend(CSD90)
        dst.extend(CSD45)
        # return
        return dst
    ## motion feature maps
    def MFMGetFM(self, src):
        # convert scale
        I8U = np.uint8(src) * 255
        # calculating optical flows
        if self.prev_frame != None:
            param1 = pySaliencyMapDefs.farne_pyr_scale
            param2 = pySaliencyMapDefs.farne_levels
            param3 = pySaliencyMapDefs.farne_winsize
            param4 = pySaliencyMapDefs.farne_iterations
            param5 = pySaliencyMapDefs.farne_poly_n
            param6 = pySaliencyMapDefs.farne_poly_sigma
            param7 = pySaliencyMapDefs.farne_flags
            flow = cv2.calcOpticalFlowFarneback(prev_frame, I8U, \
                    param1, param2, param3, param4, param5, param6, param7)
            flowx = flow[...,0]
            flowy = flow[...,1]
        else:
            flowx = np.zeros(I8U.shape)
            flowy = np.zeros(I8U.shape)
        # create Gaussian pyramids
        dst_x = self.FMGaussianPyrCSD(flowx)
        dst_y = self.FMGaussianPyrCSD(flowy)
        # update the current frame
        self.prev_frame = np.array(I8U)
        # return
        return dst_x, dst_y

    # conspicuity maps
    ## standard range normalization
    def SMRangeNormalize(self, src):
        minn, maxx, dummy1, dummy2 = cv2.minMaxLoc(src)
        if maxx!=minn:
            dst = src/(maxx-minn) + minn/(minn-maxx)
        else:
            dst = src - minn
        return dst
    ## computing an average of local maxima
    def SMAvgLocalMax(self, src):
        # size
        stepsize = pySaliencyMapDefs.default_step_local
        width = src.shape[1]
        height = src.shape[0]
        # find local maxima
        numlocal = 0
        lmaxmean = 0
        for y in range(0, height-stepsize, stepsize):
            for x in range(0, width-stepsize, stepsize):
                localimg = src[y:y+stepsize, x:x+stepsize]
                lmin, lmax, dummy1, dummy2 = cv2.minMaxLoc(localimg)
                lmaxmean += lmax
                numlocal += 1
        # averaging over all the local regions
        return lmaxmean / numlocal
    ## normalization specific for the saliency map model
    def SMNormalization(self, src):
        dst = self.SMRangeNormalize(src)
        lmaxmean = self.SMAvgLocalMax(dst)
        normcoeff = (1-lmaxmean)*(1-lmaxmean)
        return dst * normcoeff
    ## normalizing feature maps
    def normalizeFeatureMaps(self, FM):
        NFM = list()
        for i in range(0,6):
            normalizedImage = self.SMNormalization(FM[i])
            nownfm = cv2.resize(normalizedImage, (self.width, self.height), interpolation=cv2.INTER_LINEAR)
            NFM.append(nownfm)
        return NFM
    ## intensity conspicuity map
    def ICMGetCM(self, IFM):
        NIFM = self.normalizeFeatureMaps(IFM)
        ICM = sum(NIFM)
        return ICM
    ## color conspicuity map
    def CCMGetCM(self, CFM_RG, CFM_BY):
        # extracting a conspicuity map for every color opponent pair
        CCM_RG = self.ICMGetCM(CFM_RG)
        CCM_BY = self.ICMGetCM(CFM_BY)
        # merge
        CCM = CCM_RG + CCM_BY
        # return
        return CCM
    ## orientation conspicuity map
    def OCMGetCM(self, OFM):
        OCM = np.zeros((self.height, self.width))
        for i in range (0,4):
            # slicing
            nowofm = OFM[i*6:(i+1)*6]  # angle = i*45
            # extracting a conspicuity map for every angle
            NOFM = self.ICMGetCM(nowofm)
            # normalize
            NOFM2 = self.SMNormalization(NOFM)
            # accumulate
            OCM += NOFM2
        return OCM
    ## motion conspicuity map
    def MCMGetCM(self, MFM_X, MFM_Y):
        return self.CCMGetCM(MFM_X, MFM_Y)

    # core
    def SMGetSM(self, src):
        # definitions
        size = src.shape
        width  = size[1]
        height = size[0]
        # check
#        if(width != self.width or height != self.height):
#            sys.exit("size mismatch")
        # extracting individual color channels
        R, G, B, I = self.SMExtractRGBI(src)
        # extracting feature maps
        IFM = self.IFMGetFM(I)
        CFM_RG, CFM_BY = self.CFMGetFM(R, G, B)
        OFM = self.OFMGetFM(I)
        MFM_X, MFM_Y = self.MFMGetFM(I)
        # extracting conspicuity maps
        ICM = self.ICMGetCM(IFM)
        CCM = self.CCMGetCM(CFM_RG, CFM_BY)
        OCM = self.OCMGetCM(OFM)
        MCM = self.MCMGetCM(MFM_X, MFM_Y)
        # adding all the conspicuity maps to form a saliency map
        wi = pySaliencyMapDefs.weight_intensity
        wc = pySaliencyMapDefs.weight_color
        wo = pySaliencyMapDefs.weight_orientation
        wm = pySaliencyMapDefs.weight_motion
        SMMat = wi*ICM + wc*CCM + wo*OCM + wm*MCM
        # normalize
        normalizedSM = self.SMRangeNormalize(SMMat)
        smoothedSM = cv2.GaussianBlur(normalizedSM, (7,7), 1.55)
        SM = cv2.resize(smoothedSM, (width,height), interpolation=cv2.INTER_NEAREST)
        # return
        return SM