<div dir="ltr"><div class="gmail_default" style="font-family:arial,sans-serif">Matt,</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">Tiffinfo reports the following. Note the "Transparency Mask" subfile. </div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">$ tiffinfo sample-no-mask.tif<br>...<br>TIFF Directory at offset 0xe2 (226)<br> Image Width: 304 Image Length: 285<br> Tile Width: 512 Tile Length: 512<br> Bits/Sample: 8<br> Sample Format: unsigned integer<br> Compression Scheme: JPEG<br> Photometric Interpretation: YCbCr<br> YCbCr Subsampling: 2, 2<br> Samples/Pixel: 3<br> Planar Configuration: single image plane<br> Reference Black/White:<br> 0: 0 255<br> 1: 128 255<br> 2: 128 255<br> Tag 33550: 100.000000,100.000000,0.000000<br> Tag 33922: 0.000000,0.000000,0.000000,343739.586723,1091611.850704,0.000000<br> Tag 34735: 1,1,0,7,1024,0,1,1,1025,0,1,1,1026,34737,21,0,2049,34737,6,21,2054,0,1,9102,3072,0,1,3578,3076,0,1,9001<br> Tag 34737: NAD83 / Yukon Albers|NAD83|<br> JPEG Tables: (142 bytes)<br>TIFF Directory at offset 0x33a (826)<br> <font color="#cc0000">Subfile Type: transparency mask (4 = 0x4)</font><br> Image Width: 304 Image Length: 285<br> Tile Width: 512 Tile Length: 512<br> Bits/Sample: 1<br> Sample Format: unsigned integer<br> Compression Scheme: AdobeDeflate<br> Photometric Interpretation: transparency mask<br> Samples/Pixel: 1<br> Planar Configuration: single image plane<br> Predictor: none 1 (0x1)<br></div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">This is recognised by GDAL and treated as a special kind of mask as indicated in the gdalinfo report:</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">$ gdalinfo sample-no-mask.tif <br>Driver: GTiff/GeoTIFF<br>Files: sample-no-mask.tif<br>Size is 304, 285<br>...</div><div class="gmail_default" style="font-family:arial,sans-serif">Origin = (343739.586723418149631,1091611.850704099284485)<br>Pixel Size = (100.000000000000000,-100.000000000000000)<br>Metadata:<br> AREA_OR_POINT=Area<br>Image Structure Metadata:<br> COMPRESSION=YCbCr JPEG<br> INTERLEAVE=PIXEL<br> SOURCE_COLOR_SPACE=YCbCr<br>Corner Coordinates:<br>Upper Left ( 343739.587, 1091611.851) <br>Lower Left ( 343739.587, 1063111.851) <br>Upper Right ( 374139.587, 1091611.851) <br>Lower Right ( 374139.587, 1063111.851) <br>Center ( 358939.587, 1077361.851) <br>Band 1 Block=512x512 Type=Byte, ColorInterp=Red<br> Mask Flags: PER_DATASET <br>Band 2 Block=512x512 Type=Byte, ColorInterp=Green<br> Mask Flags: PER_DATASET <br>Band 3 Block=512x512 Type=Byte, ColorInterp=Blue<br> Mask Flags: PER_DATASET <br></div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">In QGIS's "Information" tab under properties I see:</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">"More Information: Mask band (exposed as alpha band)"</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">So QGIS is using the special mask as alpha. I find that if I do:</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">tiffcp sample-no-mask.tif,0 x0.tif</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">I get an "x0.tif" with just the jpeg image, and not the mask. That may be helpful for you (without uncompressing the jpeg image).</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">Best regards,</div><div class="gmail_default" style="font-family:arial,sans-serif">Frank</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jan 17, 2022 at 7:38 PM <<a href="mailto:Matt.Wilkie@yukon.ca">Matt.Wilkie@yukon.ca</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div lang="EN-CA">
<div class="gmail-m_1658317665672816008WordSection1">
<p class="MsoNormal">I’m confused. The attached image has no Nodata, but when dropped into Qgis and ArcGIS large areas are still drawn transparently, and there is no 4<sup>th</sup> band for a mask or alpha. How is this happening?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">(I’m trying to get completely rid of all Nodata and Mask info, so as to start over creating one of those from blank slate).<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal" style="margin-top:4pt;line-height:115%;vertical-align:middle">
<b><span lang="EN-US" style="font-size:10pt;line-height:115%">Matt Wilkie</span></b><span lang="EN-US" style="font-size:10pt;line-height:115%"><u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10pt">Geomatics Developer & Administrator<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10pt">Environment
<span style="color:rgb(46,116,181)">|</span> Technology, Innovation and Mapping<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10pt">T 867-667-8133
<span style="color:rgb(46,116,181)">|</span> </span><u><span style="font-size:10pt"><a href="http://yukon.ca/" target="_blank"><span lang="EN-US" style="color:windowtext">Yukon.ca</span></a><u></u><u></u></span></u></p>
<p class="MsoNormal"><i><span style="font-size:10pt">Hours: 08:30-16:30, Mon-Wed: Office, Thu: Remote, Fri: Away.<u></u><u></u></span></i></p>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><font face="monospace">---------------------------------------+--------------------------------------<br>I set the clouds in motion - turn up | Frank Warmerdam, <a href="mailto:warmerdam@pobox.com" target="_blank">warmerdam@pobox.com</a><br>light and sound - activate the windows | +1 650-701-7823<br>and watch the world go round - Rush | Geospatial Software Developer</font></div></div></div></div></div>