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<body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><span>I could be mistaken, but it looks like AreaAveragingFilter has a typo in it. This method looks suspicious to me:</span></div><div id="x8140bcb8a2f345e" style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div id="xed53aded5dd341b7956b8c6700b79786"><div><br /></div><div><div style="color:#080808;font-family:'JetBrains Mono',monospace;font-size:9.8pt;"><pre><span style="color:#0033B3;">public void </span><span style="color:#00627A;">setHints</span>(<span style="color:#0033B3;">int </span>hints) {<br /> <span style="color:#871094;">passthrough </span>= ((hints & <span style="color:#871094;font-style:italic;">neededHints</span>) != <span style="color:#871094;font-style:italic;">neededHints</span>);<br /> <span style="color:#0033B3;">super</span>.setHints(hints);<br />}</pre></div></div><div><br /></div><div>Later on the passthrough field is used as:</div><div><br /></div><div><div style="color:#080808;font-family:'JetBrains Mono',monospace;font-size:9.8pt;"><pre><span style="color:#0033B3;">public void </span><span style="color:#00627A;">setPixels</span>(<span style="color:#0033B3;">int </span>x, <span style="color:#0033B3;">int </span>y, <span style="color:#0033B3;">int </span>w, <span style="color:#0033B3;">int </span>h,<br /> <span style="color:#000;">ColorModel </span>model, <span style="color:#0033B3;">byte </span>pixels[], <span style="color:#0033B3;">int </span>off,<br /> <span style="color:#0033B3;">int </span>scansize) {<br /> <span style="color:#0033B3;">if </span>(<span style="color:#871094;">passthrough</span>) {<br /> <span style="color:#0033B3;">super</span>.setPixels(x, y, w, h, model, pixels, off, scansize);<br /> } <span style="color:#0033B3;">else </span>{<br /> accumPixels(x, y, w, h, model, pixels, off, scansize);<br /> }<br />}</pre></div></div><div><br /></div><div>This makes me think we want passthrough to be <i>true</i> when we match specific hints (“neededHints”) promising to deliver the pixel data in whole scanlines from top-to-bottom. So the “!=“ in setHints(..) should be “==“.</div><div><br /></div><div>If I set passthrough to true for BufferedImages (which always deliver pixels from top to bottom in entire scanlines), then the execution time of this filter reduces to less than 5% of its current time. But it introduces scaling artifacts and looks lower quality.</div><div><br /></div><div>So if (?) my theory is correct that there is a typo, and knowing that the AreaAveragingFilter is<span> </span><a href="https://bugs.openjdk.org/browse/JDK-6196792?jql=status = Open AND text ~ "AreaAveragingScaleFilter"" style="font-size: 9pt;">effectively internally deprecated</a><span> : is anyone interested in discussing this with me further? I attached my (very rough) test program that demonstrates both the performance difference and the scaling artifacts.</span></div><div><span><br /></span></div><div><span>(My broad goal is to create thumbnails of large images. If I used a Graphics2D to scale the image more than 50%, then I also see scaling artifacts with that approach. I know “Filthy Rich Clients” outlined a solution to that problem, but it’s expensive. So I’m dusting off this filter to see if it can work.)</span></div><div><span><br /></span></div><div>Regards,</div><div> - Jeremy</div><div></div></div>
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