proc read_png_timestamp {file} {
set fh [open $file r]
fconfigure $fh -encoding binary -translation binary -eofchar {}
if {[read $fh 8] != "\x89PNG\r\n\x1a\n"} { close $fh; return }
while {[set r [read $fh 8]] != ""} {
binary scan $r Ia4 len type
set r [read $fh [expr {$len + 4}]]
if {[string length $r] != ($len + 4)} { close $fh; return }
if {$type == "tIME"} {
binary scan $r Sccccc year month day hour minute second
close $fh
return [list $year $month $day $hour $minute $second]
}
}
close $fh
return
}--AF Returns a list in the following format: year month day hour minute second