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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Ok why does this not happen with multi band jpgs?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Even Rouault [mailto:even.rouault@mines-paris.org] <br><b>Sent:</b> Friday, April 13, 2012 1:13 PM<br><b>To:</b> gdal-dev@lists.osgeo.org<br><b>Cc:</b> Ethan Alpert<br><b>Subject:</b> Re: [gdal-dev] Problem with garbage bytes of data after EOI marker in single band JPEG<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>Le vendredi 13 avril 2012 19:53:41, Ethan Alpert a écrit :<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>> <o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>> This has been running for years. Recently a customer who receives these<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>> started scanning the JPG's for security threats. Turns out that the<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>> JPG's I've been writing have garbage data after the JPEG EOI marker.<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>><o:p> </o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-paragraph-type:empty;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>This is not garbage, but mask data appended after the JPEG data stream, as documented in the JPEG driver doc : <o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>"""The driver also supports the "zlib compressed mask appended to the file" <o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>approach used by a few data providers to add a bitmask to identify pixels that <o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>are not valid data."""<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt;-qt-paragraph-type:empty;-qt-block-indent:0;-qt-user-state:0'><span style='font-size:9.0pt;font-family:"Sans Serif","serif"'>The mask is due to the advertized nodata value in the VRT. You can likely remove it by adding <<i>HideNoDataValue</i>>1</<i>HideNoDataValue</i>> in the VRT file under the VRTRasterBand element.<o:p></o:p></span></p></div><PRE>This electronic communication and any attachments may contain confidential and proprietary
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