A method comprising: receiving a standard dynamic range SDR image comprising luma and chroma codewords and a reference backward reshaping function used to generate a reconstructed high dynamic range HDR image from the SDR image, the reference backward reshaping function comprising a reference luma backward reshaping function from SDR codewords into HDR codewords in the reconstructed HDR image; generating a SDR luma histogram based on luma codewords in the SDR image; generating a set of color preservation mapping inputs from the SDR image and the reference backward reshaping function by determining a representative color saturation value for each SDR luma histogram bin of the SDR luma histogram based on the SDR luma histogram of the SDR luma image and the chroma values corresponding to the chroma codewords of the pixels in the SDR luminance histogram; generating a color preservation mapping function based on a regression model using a set of data points collected from a population of SDR images and reconstructed HDR images from the population of SDR images; determining a plurality of luminance increases for a plurality of SDR luma histogram bins of the SDR luma histogram by using the color preservation mapping function with the set of color preservation mapping inputs; generating a modified luma backward reshaping function from the reference backward reshaping function based on the plurality of luminance increases for the plurality of SDR luma histogram bins of the SDR luma histogram; generating a modified backward reshaping function used to generate a color-preserved reconstructed HDR image from the SDR image, the modified backward reshaping function comprising the modified luma backward reshaping function; encoding and transmitting the SDR image and the modified backward reshaping function into an SDR video signal; causing a display HDR image for rendering on a display device to be generated by a recipient device of the SDR video signal based at least on the SDR image and the modified backward reshaping function in the SDR video signal. receiving a standard dynamic range SDR image comprising luma and chroma codewords and a reference backward reshaping function used to generate a reconstructed high dynamic range HDR image from the SDR image, the reference backward reshaping function comprising a reference luma backward reshaping function from SDR codewords into HDR codewords in the reconstructed HDR image; generating a SDR luma histogram based on luma codewords in the SDR image; generating a set of color preservation mapping inputs from the SDR image and the reference backward reshaping function by determining a representative color saturation value for each SDR luma histogram bin of the SDR luma histogram based on the SDR luma histogram of the SDR luma image and the chroma values corresponding to the chroma codewords of the pixels in the SDR luminance histogram; generating a color preservation mapping function based on a regression model using a set of data points collected from a population of SDR images and reconstructed HDR images from the population of SDR images; determining a plurality of luminance increases for a plurality of SDR luma histogram bins of the SDR luma histogram by using the color preservation mapping function with the set of color preservation mapping inputs; generating a modified luma backward reshaping function from the reference backward reshaping function based on the plurality of luminance increases for the plurality of SDR luma histogram bins of the SDR luma histogram; generating a modified backward reshaping function used to generate a color-preserved reconstructed HDR image from the SDR image, the modified backward reshaping function comprising the modified luma backward reshaping function; encoding and transmitting the SDR image and the modified backward reshaping function into an SDR video signal; causing a display HDR image for rendering on a display device to be generated by a recipient device of the SDR video signal based at least on the SDR image and the modified backward reshaping function in the SDR video signal.