Today’s Question: I recognize that your philosophy is to always capture and retain as much information as possible in a photo file, so your recommendation to use ProPhoto RGB [as a working color space] where possible makes sense. But realistically, to most photographers, does it really make much difference if one uses sRGB for all photos?
Tim’s Quick Answer: Realistically, in most real-world scenarios, the advantages of using ProPhoto RGB (or Adobe RGB) rather than sRGB would be very minimal. Excellent results can be achieved with the sRGB color space for most photos with most output types.
More Detail: Many photographers, including me, have a philosophy of using a workflow that helps to maximize the potential quality and amount of information available in photos. That includes, for example, capturing in raw, working in the 16-bit per channel mode, and using a wide-gamut color space when processing your photos.
The color space you use when optimizing your photos determines the total range of color values that are available. As a somewhat extreme example, if you are working in the Grayscale (rather than RGB) color mode, your image can only contain shades of gray, with no color at all. With RGB color spaces, the differences relate to which specific color values are actually available.
Among the commonly used working space color profiles, sRGB is the smallest, ProPhoto RGB is the largest, and Adobe RGB is in between. In this context, a larger color space means that colors of higher saturation are available compared to a smaller color space.
It is important to keep in mind, however, that the final output for an image determines what colors will actually be visible in that output.
For example, for images that will only be presented online, the capabilities of a monitor display determine which colors are available. Most monitor displays have a color gamut that is somewhat close to the sRGB color space, and some monitors are capable of presenting most (or all) of the colors available in the Adobe RGB color space. So, working in a color space larger than sRGB for photos that will only be presented with a digital display (such as online or in a digital slideshow) will generally provide very little benefit, if any benefit at all.
For photos that will be printed, the capabilities of the printer, ink, and paper combination determine which colors are possible in the final output. The differences with print can be significant, with most uncoated matte papers offering a relatively narrow color gamut. A wider color gamut and higher dynamic range are generally possible with glossy papers.
For certain images, especially with highly saturated colors, a wide-gamut color space such as ProPhoto RGB can absolutely result in more detail and more vibrant colors in the print. But there is no question that great results can be achieved working exclusively in the sRGB color space. That said, I would also say that there isn’t a true advantage to working in sRGB rather than a wider-gamut color space, unless you need to use an sRGB workflow for the specific output you’re producing, or if you are working with images that do not contain high-bit data.