def Ydlep_to_xyz(Ydlep, cieobs=_CIEOBS, xyzw=_COLORTF_DEFAULT_WHITE_POINT, flip_axes=False, **kwargs): """ Convert Y, dominant (complementary) wavelength and excitation purity to XYZ tristimulus values. Args: :Ydlep: | ndarray with Y, dominant (complementary) wavelength and excitation purity :xyzw: | None or narray with tristimulus values of a single (!) native white point, optional | None defaults to xyz of CIE D65 using the :cieobs: observer. :cieobs: | luxpy._CIEOBS, optional | CMF set to use when calculating spectrum locus coordinates. :flip_axes: | False, optional | If True: flip axis 0 and axis 1 in Ydelep to increase speed of loop in function. | (single xyzw with is not flipped!) Returns: :xyz: | ndarray with tristimulus values """ Ydlep3 = np3d(Ydlep).copy().astype(np.float) # flip axis so that longest dim is on first axis (save time in looping): if (Ydlep3.shape[0] < Ydlep3.shape[1]) & (flip_axes == True): axes12flipped = True Ydlep3 = Ydlep3.transpose((1, 0, 2)) else: axes12flipped = False # convert xyzw to Yxyw: Yxyw = xyz_to_Yxy(xyzw) Yxywo = Yxyw.copy() # get spectrum locus Y,x,y and wavelengths: SL = _CMF[cieobs]['bar'] wlsl = SL[0, None].T Yxysl = xyz_to_Yxy(SL[1:4].T)[:, None] # center on xyzw: Yxysl = Yxysl - Yxyw Yxyw = Yxyw - Yxyw #split: Y, dom, pur = asplit(Ydlep3) Yw, xw, yw = asplit(Yxyw) Ywo, xwo, ywo = asplit(Yxywo) Ysl, xsl, ysl = asplit(Yxysl) # loop over longest dim: x = np.empty(Y.shape) y = np.empty(Y.shape) for i in range(Ydlep3.shape[1]): # find closest wl's to dom: #wlslb,wlib = meshblock(wlsl,np.abs(dom[i,:])) #abs because dom<0--> complemtary wl wlib, wlslb = np.meshgrid(np.abs(dom[:, i]), wlsl) dwl = np.abs(wlslb - wlib) q1 = dwl.argmin(axis=0) # index of closest wl dwl[q1] = 10000.0 q2 = dwl.argmin(axis=0) # index of second closest wl # calculate x,y of dom: x_dom_wl = xsl[q1, 0] + (xsl[q2, 0] - xsl[q1, 0]) * ( np.abs(dom[:, i]) - wlsl[q1, 0]) / (wlsl[q2, 0] - wlsl[q1, 0] ) # calculate x of dom. wl y_dom_wl = ysl[q1, 0] + (ysl[q2, 0] - ysl[q1, 0]) * ( np.abs(dom[:, i]) - wlsl[q1, 0]) / (wlsl[q2, 0] - wlsl[q1, 0] ) # calculate y of dom. wl # calculate x,y of test: d_wl = (x_dom_wl**2.0 + y_dom_wl**2.0)**0.5 # distance from white point to dom d = pur[:, i] * d_wl hdom = math.positive_arctan(x_dom_wl, y_dom_wl, htype='deg') x[:, i] = d * np.cos(hdom * np.pi / 180.0) y[:, i] = d * np.sin(hdom * np.pi / 180.0) # complementary: pc = np.where(dom[:, i] < 0.0) hdom[pc] = hdom[pc] - np.sign(dom[:, i][pc] - 180.0) * 180.0 # get positive hue angle # calculate intersection of line through white point and test point and purple line: xy = np.vstack((x_dom_wl, y_dom_wl)).T xyw = np.vstack((xw, yw)).T xypl1 = np.vstack((xsl[0, None], ysl[0, None])).T xypl2 = np.vstack((xsl[-1, None], ysl[-1, None])).T da = (xy - xyw) db = (xypl2 - xypl1) dp = (xyw - xypl1) T = np.array([[0.0, -1.0], [1.0, 0.0]]) dap = np.dot(da, T) denom = np.sum(dap * db, axis=1, keepdims=True) num = np.sum(dap * dp, axis=1, keepdims=True) xy_linecross = (num / denom) * db + xypl1 d_linecross = np.atleast_2d( (xy_linecross[:, 0]**2.0 + xy_linecross[:, 1]**2.0)**0.5).T[:, 0] x[:, i][pc] = pur[:, i][pc] * d_linecross[pc] * np.cos( hdom[pc] * np.pi / 180) y[:, i][pc] = pur[:, i][pc] * d_linecross[pc] * np.sin( hdom[pc] * np.pi / 180) Yxy = np.dstack((Ydlep3[:, :, 0], x + xwo, y + ywo)) if axes12flipped == True: Yxy = Yxy.transpose((1, 0, 2)) else: Yxy = Yxy.transpose((0, 1, 2)) return Yxy_to_xyz(Yxy).reshape(Ydlep.shape)
def xyz_to_Ydlep(xyz, cieobs=_CIEOBS, xyzw=_COLORTF_DEFAULT_WHITE_POINT, flip_axes=False, **kwargs): """ Convert XYZ tristimulus values to Y, dominant (complementary) wavelength and excitation purity. Args: :xyz: | ndarray with tristimulus values :xyzw: | None or ndarray with tristimulus values of a single (!) native white point, optional | None defaults to xyz of CIE D65 using the :cieobs: observer. :cieobs: | luxpy._CIEOBS, optional | CMF set to use when calculating spectrum locus coordinates. :flip_axes: | False, optional | If True: flip axis 0 and axis 1 in Ydelep to increase speed of loop in function. | (single xyzw with is not flipped!) Returns: :Ydlep: | ndarray with Y, dominant (complementary) wavelength and excitation purity """ xyz3 = np3d(xyz).copy().astype(np.float) # flip axis so that shortest dim is on axis0 (save time in looping): if (xyz3.shape[0] < xyz3.shape[1]) & (flip_axes == True): axes12flipped = True xyz3 = xyz3.transpose((1, 0, 2)) else: axes12flipped = False # convert xyz to Yxy: Yxy = xyz_to_Yxy(xyz3) Yxyw = xyz_to_Yxy(xyzw) # get spectrum locus Y,x,y and wavelengths: SL = _CMF[cieobs]['bar'] wlsl = SL[0] Yxysl = xyz_to_Yxy(SL[1:4].T)[:, None] # center on xyzw: Yxy = Yxy - Yxyw Yxysl = Yxysl - Yxyw Yxyw = Yxyw - Yxyw #split: Y, x, y = asplit(Yxy) Yw, xw, yw = asplit(Yxyw) Ysl, xsl, ysl = asplit(Yxysl) # calculate hue: h = math.positive_arctan(x, y, htype='deg') hsl = math.positive_arctan(xsl, ysl, htype='deg') hsl_max = hsl[0] # max hue angle at min wavelength hsl_min = hsl[-1] # min hue angle at max wavelength dominantwavelength = np.empty(Y.shape) purity = np.empty(Y.shape) for i in range(xyz3.shape[1]): # find index of complementary wavelengths/hues: pc = np.where( (h[:, i] >= hsl_max) & (h[:, i] <= hsl_min + 360.0) ) # hue's requiring complementary wavelength (purple line) h[:, i][pc] = h[:, i][pc] - np.sign( h[:, i][pc] - 180.0 ) * 180.0 # add/subtract 180° to get positive complementary wavelength # find 2 closest hues in sl: #hslb,hib = meshblock(hsl,h[:,i:i+1]) hib, hslb = np.meshgrid(h[:, i:i + 1], hsl) dh = np.abs(hslb - hib) q1 = dh.argmin(axis=0) # index of closest hue dh[q1] = 1000.0 q2 = dh.argmin(axis=0) # index of second closest hue dominantwavelength[:, i] = wlsl[q1] + np.divide( np.multiply((wlsl[q2] - wlsl[q1]), (h[:, i] - hsl[q1, 0])), (hsl[q2, 0] - hsl[q1, 0]) ) # calculate wl corresponding to h: y = y1 + (y2-y1)*(x-x1)/(x2-x1) dominantwavelength[:, i][pc] = -dominantwavelength[:, i][ pc] #complementary wavelengths are specified by '-' sign # calculate excitation purity: x_dom_wl = xsl[q1, 0] + (xsl[q2, 0] - xsl[q1, 0]) * (h[:, i] - hsl[ q1, 0]) / (hsl[q2, 0] - hsl[q1, 0]) # calculate x of dom. wl y_dom_wl = ysl[q1, 0] + (ysl[q2, 0] - ysl[q1, 0]) * (h[:, i] - hsl[ q1, 0]) / (hsl[q2, 0] - hsl[q1, 0]) # calculate y of dom. wl d_wl = (x_dom_wl**2.0 + y_dom_wl**2.0)**0.5 # distance from white point to sl d = (x[:, i]**2.0 + y[:, i]**2.0)**0.5 # distance from white point to test point purity[:, i] = d / d_wl # correct for those test points that have a complementary wavelength # calculate intersection of line through white point and test point and purple line: xy = np.vstack((x[:, i], y[:, i])).T xyw = np.hstack((xw, yw)) xypl1 = np.hstack((xsl[0, None], ysl[0, None])) xypl2 = np.hstack((xsl[-1, None], ysl[-1, None])) da = (xy - xyw) db = (xypl2 - xypl1) dp = (xyw - xypl1) T = np.array([[0.0, -1.0], [1.0, 0.0]]) dap = np.dot(da, T) denom = np.sum(dap * db, axis=1, keepdims=True) num = np.sum(dap * dp, axis=1, keepdims=True) xy_linecross = (num / denom) * db + xypl1 d_linecross = np.atleast_2d( (xy_linecross[:, 0]**2.0 + xy_linecross[:, 1]**2.0)**0.5).T #[0] purity[:, i][pc] = d[pc] / d_linecross[pc][:, 0] Ydlep = np.dstack((xyz3[:, :, 1], dominantwavelength, purity)) if axes12flipped == True: Ydlep = Ydlep.transpose((1, 0, 2)) else: Ydlep = Ydlep.transpose((0, 1, 2)) return Ydlep.reshape(xyz.shape)