#!/bin/bash
# Create a PDF file from a JPEG file losslessly
# This works by creating on the fly a PDF file with just one picture and 
# resizing the page to the size of the picture.

# jpg2pdf file.jpg

basedir="$(dirname "$0")"
infile="$1"
outfile="$(dirname "$infile")/$(basename "$(basename "$infile" .jpg)" .JPG ).pdf"

LENGTH=$(stat -c "%s" "$infile")
#HEIGHT=$(exif -t 0xa003 "$infile" | grep Value | sed -r "s/.*: ([[:digit:]]+)/\1/")
HEIGHT=$(identify -format "%[fx:h]" "$infile")
#WIDTH=$(exif -t 0xa002 "$infile" | grep Value | sed -r "s/.*: ([[:digit:]]+)/\1/")
WIDTH=$(identify -format "%[fx:w]" "$infile")
#DPI=300 # $(exif -t 011a "$infile" | grep Value | sed -r "s/.*: ([[:digit:]]+)/\1/")
DPI=$(identify -format "%x" "$infile" | sed -r "s/([[:digit:]]+).*/\1/")

COLORSPACE=$(identify -format "%r" "$infile")
BPC=$(identify -format "%q" "$infile") # or %z?

# same in user unit (1/72 of inch)
HEIGHTU=$(echo "scale=5; ($HEIGHT * 72) / $DPI" | bc)
WIDTHU=$(echo "scale=5; ($WIDTH * 72) / $DPI" | bc)

# Need to handle also the colorspace : /DeviceGray /DeviceCMYK /DeviceRGB
# Need to handle the bit-per components

# Put the header
#sed -r "s/LENGTH/$LENGTH/; s/HEIGHT/$HEIGHT/; s/WIDTH/$WIDTH/" "$basedir/jpg2pdf.header" > "$outfile"u

# Put the picture
cat - "$infile" > "$outfile"u << ENDHEADER
%PDF-1.4
%âãÏÓ
1 0 obj 
<<
/ColorSpace /DeviceRGB
/Subtype /Image
/Filter /DCTDecode
/Length $LENGTH
/Width $WIDTH
/Type /XObject
/Height $HEIGHT
/BitsPerComponent 8
>>
stream
ENDHEADER

# Put the footer
#sed -r "s/HEIGHTU/$HEIGHTU/; s/WIDTHU/$WIDTHU/" "$basedir/jpg2pdf.footer" >> "$outfile"u
cat - >> "$outfile"u << ENDFOOTER
endstream 
endobj 
2 0 obj 
<<
/XObject 
<<
/Im1 1 0 R
>>
/ProcSet [/PDF /ImageC]
>>
endobj 
3 0 obj 
<<
/Parent 4 0 R
/MediaBox [0 0 $WIDTHU $HEIGHTU]
/Resources 2 0 R
/pdftk_PageNum 1
/Contents 5 0 R
/Type /Page
>>
endobj 
5 0 obj 
<<
/Length 90
>>
stream
$WIDTHU 0 0 $HEIGHTU 0 0 cm
/Im1 Do

endstream 
endobj 
4 0 obj 
<<
/Kids [3 0 R]
/Count 1
/Type /Pages
>>
endobj 
6 0 obj 
<<
/Pages 4 0 R
/Type /Catalog
>>
endobj 
7 0 obj 
<<
/Creator (jpg2pdf)
/Producer (jpg2pdf)
/Trapped /False
/ModDate (D:20070528134713+02'00')
/CreationDate (D:20070528134713+02'00')
>>
endobj xref
0 8
0000000000 65535 f 
trailer

<<
/Info 7 0 R
/Root 6 0 R
/Size 8
/ID [<62a07446f9d6fda650d12201a75fa046> <62a07446f9d6fda650d12201a75fa046>]
>>
startxref
534941
%%EOF
ENDFOOTER

# Compile (compress)
pdftk "$outfile"u output "$outfile" compress
rm -f "$outfile"u