A computer-implemented method, comprising: receiving an infrared photograph of a tangible product having an imprinted markup on the tangible product; receiving a visible light photograph of the same product with the same imprinted markup, wherein the imprinted markup is visible in the visible light photograph but is not visible in the infrared photograph; wherein the imprinted markup is imprinted upon the tangible product using a dye that is visible only in a visible light spectrum and therefore visible only in the visible light photograph, and not visible when imaged using a spectral sampling in the infrared photograph; determining, based, in part, on the infrared photograph and visible light photograph, instructions for rendering a customization image of the tangible product depicting a particular customization; wherein the instructions for rendering the customization image of the tangible product comprise one or more computer programs, scripts, or other software elements; wherein the instructions for rendering the customization image of the tangible product depicting the particular customization indicate that a color of a particular location in the particular customization is determined by modifying a color of the particular location in the visible light photograph using a luminance value associated with the particular location in the infrared photograph; wherein the luminance value associated with the particular location in the infrared photograph indicates luminance of a respective pixel located at the particular location in the infrared photograph; and wherein the particular customization is not in the infrared photograph or the visible light photograph; wherein the method is performed by one or more computing devices (104, 112). receiving an infrared photograph of a tangible product having an imprinted markup on the tangible product; receiving a visible light photograph of the same product with the same imprinted markup, wherein the imprinted markup is visible in the visible light photograph but is not visible in the infrared photograph; wherein the imprinted markup is imprinted upon the tangible product using a dye that is visible only in a visible light spectrum and therefore visible only in the visible light photograph, and not visible when imaged using a spectral sampling in the infrared photograph; determining, based, in part, on the infrared photograph and visible light photograph, instructions for rendering a customization image of the tangible product depicting a particular customization; wherein the instructions for rendering the customization image of the tangible product comprise one or more computer programs, scripts, or other software elements; wherein the instructions for rendering the customization image of the tangible product depicting the particular customization indicate that a color of a particular location in the particular customization is determined by modifying a color of the particular location in the visible light photograph using a luminance value associated with the particular location in the infrared photograph; wherein the luminance value associated with the particular location in the infrared photograph indicates luminance of a respective pixel located at the particular location in the infrared photograph; and wherein the particular customization is not in the infrared photograph or the visible light photograph; wherein the method is performed by one or more computing devices (104, 112).