I am a major supplier of scanned and 'cleaned' sheet music titles of music for violin and/or viola music up to three players, rarely, 4 or more.
My website is http://www.classicalSHEETmusicGRATIS.org, and it includes music that I have prepared since May of 2012 (most of which I upload to IMSLP). Included is an assemblage of music for STRING ORCHESTRA.
"Google" IMSLP JDH or IMSLP John Howard for my contributions to IMSLP.
Much larger in quantity are the contents of 5 cds sold on Ebay for under $10 each. See http://myworld.ebay.com/footepaine?_trksid=p2047675.l2559 Each one represents 1 or more years of work, starting in 2004.
A few details about how I prepare most sheet music images: Software used: Adobe Photoshop 6, GIMP, Pdfill and Kodak Imaging for Windows. When a file is split into individual pages, each page is improved by cleaning, straightening and letter-sizing. The sizing is done in such a way as to make the content as large as possible, or to make it as enlarge-able as possible without loss of content. To accomplish this, items like page numbers or plate numbers that are above or below the musical content are repositioned (sometimes, deleted) closer to the musical content (i.e., staves).
I may be reached at johnhoward [at] alum.swarthmore.edu See also http://classicaltrio.com