<div dir="ltr"><div>The reason for the different appearance in the histogram displays is that the</div><div>value used in each case is not really the same kind of answer. A histogram</div><div>is a bunch of "bins" (accumulators) that count the number of times a particular</div><div>pixel channel intensity occurs in an image. Dim are on the left, bright on the right.</div><div><br></div><div>The number of bins used depends on the color model bit depth, <br></div><div>histogram: 256 for rgb8 and 65536 for all others.</div><div>bezier: 256 for rgb8/yuv8 and 65536 for all others.</div><div>scope: always uses 65536</div><div><br></div><div>All of the bins are scanned when the graph is plotted. What is shown depends</div><div>on which plugin is used.</div><div>histogram: was max of the bins in the pixel range, now is the sum</div><div>bezier: is the max of the bins in the pixel range</div><div>scope: is the max of the bins in the pixel range</div><div><br></div><div>When the color space and the bin size are the same, all of the values increment</div><div>the indexed bins. When the color is the result of yuv->rgb conversion, the results</div><div>"spread" if there are more bins than colors. This is the same effect you see when</div><div>you turn on "smoothing" in the vectorscope histogram.</div><div><br></div><div>The "total" pixels for each value is approximately the same, but the "max" value</div><div>depends on the color quantization. More colors increment more bins. Fewer</div><div>colors increment fewer bins. In both cases, the image size has the same number</div><div>of pixels. The fewer color case increments the used bins, and skips the unused</div><div>bins. This sums all of the pixels into fewer bins, and the bins have higher values.</div><div>That is the "rgb" vs "yuv" case, fewer vs more bins are used.</div><div><br></div><div>To report something more consistent, I have changed the reported value to the</div><div>"sum" of the accumulated counts for the bins reporting a pixel bar on the graph.</div><div>The effect of this is to do this:</div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace"> 1<br></span></div><div><span style="font-family:monospace"> 1 1<br></span></div><div><span style="font-family:monospace">000100 3 pixels vs 0011000 3 pixels</span></div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace">On the left, the course color model piles all 3 pixels into one bin. max value 3</span></div><div><span style="font-family:monospace">On the right, the fine color model puts the counts into 2 bins, max 2, sum 3</span></div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace">So, by reporting the sum the shape of the results are more similar.</span></div><div><br></div><div>gg<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Sep 27, 2020 at 4:02 AM Igor BEGHETTO via Cin <<a href="mailto:cin@lists.cinelerra-gg.org">cin@lists.cinelerra-gg.org</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">Thanks Phyllis for your tests and GG for looking for.<br>
I don't think you are misunderstanding.<br>
I saw your video. I think it depends a bit from the video you are using <br>
for the test: your clip is an animation. I can wrong. In your screencast <br>
the histogram, in the Histogram Bezier, changes very, very, little.<br>
Please, take a look at my screencast: <a href="https://streamable.com/3svwkd" rel="noreferrer" target="_blank">https://streamable.com/3svwkd</a><br>
As you can see, the histogram, in the Histogram Bezier, doesn't change <br>
as in the Histogram.<br>
<br>
More, you can see that when I enable the Histogram Bezier plugin a <br>
little change occurs in the histogram of the View Scope. Mmh, very <br>
strange. It is like if Histogram Bezier changes the Color Model of the <br>
project, but I am guessing.<br>
<br>
I am not saying it is "wrong", I think that it is really weird that <br>
tools that perform the same function (draw an histogram) don't show the <br>
same output, I would think.<br>
<br>
IgorBeg<br>
<br>
<br>
Il 27/09/2020 03:05, Phyllis Smith via Cin ha scritto:<br>
> IgorBeg,<br>
> GG thoroughly reviewed the Histogram code to understand how it works <br>
> so he could find any bugs. He says it is all working correctly as far <br>
> as he can tell.<br>
><br>
> But about the following:<br>
><br>
> When the Color Model format (in Settings->Format...) is set to RGB[A]<br>
> the histogram displayed on Histogram plugins is the same as on<br>
> Histogram<br>
> Bezier plugin.<br>
> If you change Color Model format from RGB[A] to YUV[A] the<br>
> histogram on<br>
> Histogram Bezier no changes, but on Histogram plugin and on View<br>
> Scopes<br>
> it changes. It is strange, I think.<br>
> In Histogram Bezier plugin the histogram doesn't change in the<br>
> differents color model.<br>
><br>
> we see in <a href="https://streamable.com/vr5srs" rel="noreferrer" target="_blank">https://streamable.com/vr5srs</a> that Histogram Bezier DOES <br>
> CHANGE between the formats of RGBA and YUVA (note that I have set the <br>
> slider all the way to Log in order to compare the same thing). You <br>
> have to watch the Histogram Bezier graph specifically, but you <br>
> definitely see it change. If I am misunderstanding the concern, <br>
> please let me know.<br>
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</blockquote></div>