<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
@font-face
{font-family:"Segoe UI";
panose-1:2 11 5 2 4 2 4 2 2 3;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.msonormal0, li.msonormal0, div.msonormal0
{mso-style-name:msonormal;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-CA" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">For those not wanting or needing to take the processing hit of running nearblack, use gdalwarp and -dstalpha to create the alpha channel,
and use intermediate VRT to save space and more time. Something like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas;background:#E7ECFA">gdalwarp -srcnodata 0 -dstalpha -of vrt source.tif xx-interim.vrt<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas;background:#E7ECFA">gdal_translate -of COG {...} xx-interim.vrt final.tif </span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-Matt</span><i><span style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p></o:p></span></i></p>
</div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal-dev <gdal-dev-bounces@lists.osgeo.org>
<b>On Behalf Of </b>Travis Kirstine<br>
<b>Sent:</b> July 22, 2022 9:04 AM<br>
<b>To:</b> gdal dev <gdal-dev@lists.osgeo.org><br>
<b>Subject:</b> Re: [gdal-dev] JPEG compressed COGs nodata<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0" align="left" width="100%" style="width:100.0%">
<tbody>
<tr>
<td style="background:#A6A6A6;padding:5.25pt 1.5pt 5.25pt 1.5pt"></td>
<td width="100%" style="width:100.0%;background:#EAEAEA;padding:5.25pt 3.75pt 5.25pt 11.25pt;word-wrap:break-word">
<div>
<p class="MsoNormal" style="mso-element:frame;mso-element-frame-hspace:1.8pt;mso-element-wrap:around;mso-element-anchor-vertical:paragraph;mso-element-anchor-horizontal:column;mso-height-rule:exactly">
<span style="font-size:9.0pt;font-family:"Segoe UI",sans-serif;color:#212121">You don't often get email from
<a href="mailto:traviskirstine@gmail.com">traviskirstine@gmail.com</a>. <a href="https://aka.ms/LearnAboutSenderIdentification">
Learn why this is important</a><o:p></o:p></span></p>
</div>
</td>
<td width="10" style="width:56.25pt;background:#EAEAEA;padding:5.25pt 3.75pt 5.25pt 3.75pt;word-wrap:break-word;align:left">
</td>
</tr>
</tbody>
</table>
<div>
<div>
<div>
<p class="MsoNormal">To answer my own question I believe the answer is that you need to create an alpha band when working with RGB datasets to have JPEG compressed COGs without compression artifacts in the nodata areas. Creating a internal mask on the source
data may work as well but I haven't tried.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"># add a alpha band using the nearblack utility<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">nearblack -setalpha rgb_nodata.tif -o rgba.tif<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"># create the COG<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">gdal_translate -of COG -co COMPRESS=JPEG -co TILING_SCHEME=GoogleMapsCompatible -co NUM_THREADS=ALL_CPUS -co BIGTIFF=YES rgba.tif cog.tif<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Regards<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Tue, 19 Jul 2022 at 15:19, Travis Kirstine <<a href="mailto:traviskirstine@gmail.com">traviskirstine@gmail.com</a>> wrote:<o:p></o:p></p>
</div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm">
<div>
<div>
<p class="MsoNormal">I've been trying to create a COG with JPEG compression with transparent nodata values without much success. Is this possible without creating a secondary mask?
<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Any hints?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Regards<o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
</div>
</div>
</body>
</html>