George Seurat first employed his divisionist painting technique on A Sunday on La Grande Jatte—1884 beginning in October 1885. Painting with pigments representing colors seen in the visible spectrum that were minimally mixed on the palette and using divided brushstrokes, he aimed to impart luminosity to the surface and to explore 19th century ideas of color theory, such as simultaneous contrast. Pigment analysis has disclosed that the brushwork containing zinc yellow has darkened significantly: Yellow, green-yellow, and orange brushstrokes have become brown, olive-green, and reddish brown, respectively. Additionally, the painting has further darkened due to the natural aging of the oil medium. By performing spectral reflectance measurements in-situ on darkened areas of the painting and on paint-outs of comparable unaltered colors, using Kubelka-Munk turbid media theory, imaging the painting with colormanaged digital photography, and image editing with Adobe Photoshop, a digital version of the original, more luminous appearance of La Grande Jatte was simulated.