This small-formatted book was put together by one of the conservationist at the National Gallery in London
(Jill Dunkerton is responsible for the very interesting Giotto to Dürer: http://www.goodreads.com/book/show/800955.Giotto_to_Durer)
The book contains a set of 50-60 highly magnified details drawn from various Italian and Netherlandish paintings of the 15th cen., accompanied by small prints of entire pictures (in their entirey) from which these details were drawn.
In the full picture, there are tiny white numbered circles showing where the details are from. But these white circles completely blot out what the detail looked like in their context, in the full picture, which greatly detracts from the value of looking at the details in isolation. There's nothing to compare them to.
Furthermore, there is very little text (though what text there is, is of real interest) -- far too little to make the significance of these details, suggestive though they are, clear to the layman's eyes.
It's a fabulous idea, bringing us into the artist's workshop in this way -- but its execution was not carried through by the authors.
There is another "in the workshop" book by Anthea Callen on the Impressionists, which I have and have been meaning to read -- which is much fuller and looks to be somewhat more successful: