The imagePROGRAF PRO-300 and imagePROGRAF PRO-1000 both feature an additional ink tank called the Chroma Optimiser, which helps to produce prints with uniform glossiness. During printing, Chroma Optimiser is laid over the top of the print, a bit like a clear coat. This has the effect of filling in the gaps between the different ink droplets and so creating a uniform layer of ink with no troughs or ridges. As a result, light can reflect back from the print evenly, giving a uniform level of glossiness across the entire print. In darker tones, Chroma Optimiser will also increase the colour gamut of the print – because it reflects less light back than black ink alone, it has the effect of showing the true depth of the blacks in a print.
For both colour and monochrome printing, the Chroma Optimiser coating also reduces bronzing. Bronzing is a reflectance phenomenon where tones in the print, especially grey tones, take on an iridescent appearance, a lot like bronze metal. This effect is closely related to metamerism, where two colours can appear to match under one set of lighting conditions but look different under different lighting conditions (like when you put on a pair of socks and only later discover that one is black but the other is navy blue). The use of Chroma Optimiser will reduce both these effects, giving a more visually pleasing result that is also more colour-accurate.