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In compositor, I have two image sequence input nodes. Both image sequences contain 300 images.

In the output (either Viewer, Composite or File Output) I want to blend from "100% first ,0% second image sequence" to "0% first, 100% second image sequence".

I tried to use a Mix node which takes the two image sequences as inputs, but per default, it seems as if both image sequences are mixed together at the output, even at factor 0.

It really is of essential importance for me to have image sequence 1 exclusively at the beginning and number 2 in the end. Meaning the first image at the output should be exactly the first image from sequence 1 and the last image at the output should be exactly the last image of sequence 2. In the middle, I wanted to look for the "sweet spot" of blending with the factor setting. How can I achieve something like this?

Here is the current compositor in order to support my description:

enter image description here

Edit: Here is a demo file with only single image inputs, but the same effect. I want at a factor of 0, that the output should be exactly the same as the upper input image.

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  • $\begingroup$ What leads you think -images are already mixed a bit at Factor zero (or one)? By switching image directly to Viewer and Mix output socket I don't see a difference. Thanks for more info. $\endgroup$
    – vklidu
    Sep 7, 2022 at 6:44
  • $\begingroup$ You are correct that at first glimpse it looks like there is no difference. I was confused also when I made this small example and checked if everything is "working" as expected. Then I saved the image from the rendered view to disk as png and compared it with an image viewer (Irfanview) to the one that I input and the "rendered" image was slightly but clearly brighter than the original one. $\endgroup$
    – Kiamur
    Sep 7, 2022 at 6:58
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    $\begingroup$ Isn't that caused by Colour Management that is by default set to Filmic? $\endgroup$
    – vklidu
    Sep 7, 2022 at 7:01
  • $\begingroup$ Maybe it is... I'll check. Thanks! $\endgroup$
    – Kiamur
    Sep 7, 2022 at 7:02
  • $\begingroup$ Looks like this is going into the right direction. When I change to standard in the render properties, the viewer immediately reacts and the output gets less bright. Just what I want. Now, the only problem left is that the rendered output is still brighter, although the color management of the output properties should follow the scene and also the override seems to make no difference. I'm confused... $\endgroup$
    – Kiamur
    Sep 7, 2022 at 7:14

2 Answers 2

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If I understood you right - just animate Fac (Factor) value of Mix node, add keyframe at frame 1 with value zero ...

enter image description here

... than move timeline at last frame, set value to 1 and add another keyframe (with cursor hovering above value field press "I" or right click for context menu).

enter image description here

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  • $\begingroup$ Thanks for taking the effort answering. However, this is the issue I'm actually asking about. I thought "factor=0" leads to 100% image 1 and "factor=1" leads to 100% second image. This is not the case. Even at "factor=0" it seems as if both images are mixed together already a little bit. I'm looking for a way to have a mixer which does not mix anything if the factor is at its limit. $\endgroup$
    – Kiamur
    Sep 7, 2022 at 5:32
  • $\begingroup$ @Kiamur As vklidu stated, that's how it works and you understand the mixing correctly. However, what I see in your screenshot above is ####.png for the first image sequence and ####.png.001 for the second image sequence. This looks like the second is a duplicate of the first one - in this case they are the same (the preview image looks the same, too), so how would you recognize which one the Mix RGB really shows? $\endgroup$
    – Gordon Brinkmann
    Sep 7, 2022 at 7:25
  • $\begingroup$ The difference of the input images is very subtle. Both in view and naming. The images are named 0001_08.png and 0001_80.png. They were rendered from the same scene, but one with 8 transparency light bounces and the other with 80. Since I'm a beginner, I realized pretty far in my project that I need more light bounces than 8 in my scene, when the sun will rise (later in the animation). So I want to fade the 8-images into the 80-images, in order to "fix my mistake in post" ;-) (The screenshot from my initial post is not from the sample blend file I provided, download that and see for yourself). $\endgroup$
    – Kiamur
    Sep 7, 2022 at 7:32
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The problem was solved with the hint of vklidu, regarding the "filmic" setting in the color management properties and the following discussion with Gordon Brinkmann.

Explanation: I asked the wrong question due to my lack of awareness of the "filmic" option. I believed, that the Mix Node is affecting my input images although the factor was set to 0 or 1 respectively. By comparing the input image to the image rendered out external of Blender (with a simple image viewer), there is a difference when the Color management is set to filmic. The images are exactly the same, when the color management is set to standard.

The Mix node works just as expected!

For completeness, here are the original input file, the filmic output and the standard output (in exactly that order).

enter image description here

enter image description here

enter image description here

Finally, the setting I had to change

enter image description here

Be aware, that color management settings are at different places, for different purposes (view, render, file output).

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