"Interstices" 24 x 24"I'm a self-taught painter in a young, North American city. Our galleries are largely contemporary or landscape and there is a lot of Western art. There is no place to go and see the historical European masters of painting and enrolling in a BFA program is not in my cards. In this situation, becoming a unique painter used to be tough. It's not anymore.
Most of what I learned came from the library. Not just those "How to Paint a Tree in Oils" books which are, briefly, a great tool, but also the massive, coffee-table books full of high quality reproductions of the greats. I've borrowed the series of books about John Singer Sargent written by Richard Ormond so many times that they seem like my own. Rembrandt, Manet, Degas, Morisot: all are available for me to examine and think about. The best of them have detailed, crisp close ups of a small section of the painting. In the book: Women Impressionists, there is a detail of a woman's sleeve, painted by Berthe Morisot which is a revelation. The layering and choices of colour and unique, zigzag brushwork are clearly visible.
After a couple of years with the library as my main resource, I turned to the Internet. All galleries put their works online and, a few of them have really great quality images. (Most don't.)
The best one that I've found so far is Greenhouse Gallery in San Antonio, Texas. Their photographer is amazing. None of the paintings are ever out of focus or obscured by glare and the colours never show an imbalance (blues can easily take over a digital photo; I don't know why.) But the best thing is the function which allows you to see each work at high resolution. It takes a little longer to load but the painting fills the screen and then some. Each brushstroke is visible and colours that would be impossible to discern in a 3x4" image suddenly appear in large format.
The gallery contains works by contemporary realists and impressionists, by big names and small, but the quality of the work is uniformly high.
They also maintain an archive of sold works by each artist which is still available in high resolution.
For the study of painting when you have little access to original art, this site can't be beat.