なんか画質悪い

tell application "Finder"
if (exists of file "ss.jpg" of (path to desktop folder)) is true then
set var to 2
repeat
if (exists of file ("ss " & var & ".jpg") of (path to desktop folder)) is false then
set fileName to "ss' '" & var & ".jpg"
exit repeat
else
set var to var + 1
end if
end repeat
else
set fileName to "ss.jpg"
end if
end tell

do shell script "screencapture -t'JPEG' ~/Desktop/" & fileName