Loader node sometimes loads image differently than MediaIn

As per a tip from TheBloke, I am replacing my MediaIn nodes with Loader nodes for the images I'm using in compositions. Sometimes, however, the image looks different than what the MediaIn node had before. It must either be loading a different file, or a different version of the file, but neither of those make a lot a sense to me. At first I thought it might be a cache thing, but purging the cache and re-rendering the current frame doesn't fix it, and neither does closing Resolve and opening it again. I can confirm by opening the file in Windows that the version shown in the MediaIn node is correct, so it's even weirder to me that the loader node is displaying the wrong thing, since it was just now added to the composition, and just now pointed to the correct file.

In this image, the same file is loaded in both nodes:

loaderNode.png (123.54 KiB) Viewed 1967 times

Any ideas?

Loader trusts the user more than most software. It doesn't automatically premultiply PNGs, trusting that the compositor will choose to handle the file in the way that seems best to them. This has the side effect of avoiding the problem of a double-multiplication that can happen if someone exports an associated alpha with their PNG.

In the Import tab, check the Post-Multiply by Alpha switch, and it should appear as you expect. Alternately, you could add an AlphaMultiply node immediately after the Loader. (But don't do both!)

Loader trusts the user more than most software.

Sounds good so far.

That doesn't seem to be the issue though. Here are two screenshots, one before and one after I checked post-multiply; you can see it causes no changes whatsoever. And a clarifying question: why would post-multiply add a border to the shapes within the original image? I'll admit that I don't really remember what it does (I'll look into it again - clearly I should), but if anything, wouldn't it swap the alpha/non-alpha areas?

That does look a bit weird. Can you upload that PNG? Attach it here, or Google Drive/Dropbox it if it's too big to attach.

I can't publicly post my full-res assets, and I feel like if I made a new file in order to make it smaller, it would be likely that whatever issue there might be with the file itself wouldn't carry over to the new png. Maybe I could email you directly? Please PM me if that works for you. Thanks.

OK so I drag it in Fusion Studio to make a Loader with all default settings and it looks fine to me:



I go to Resolve Studio and add a Loader, browse to the file, and it works fine



So I'm quite confused about what you're seeing.

Those white areas seen in the Fusion Studio screenshot are caused by the Loader Format -> Multiply By Alpha tickbox, which was off by default in Fusion Studio and on by default in Resolve Studio. So ticking that makes those white areas disappear, but does not fill in the shapes for me. Those white areas show as RGB = 1.0 but A = 0. However if I load the file in Photoshop, I can't see any white pixels in the corners. So there is something odd there too.

I can't find any change in the Loader that fills in the shapes, and I'm struggling to think what process could cause that. In the Inspector I can see that Alpha = 0 everywhere except in the outline.

As a final check, I loaded it in Fusion Studio 17.3.1 in Windows 10, just in case there was some OS difference. Same result. I can't easily test Resolve on Windows as I'm testing in a virtual machine and Resolve won't load in a VM, I'd have to reboot into Windows.

Sanity check: you're certain this is the same version of the file you're loading in both instances, and that you sent to me? There are no other versions of that file?

Sanity check: you're certain this is the same version of the file you're loading in both instances, and that you sent to me? There are no other versions of that file?

Definitely. The only thing I can think of is that I probably changed the file by overwriting it with the same name at some point. Still though, this shouldn't really matter, at least if I've closed and re-opened the project since then, right?

If you've restarted Resolve then yes it would always load the current version of the file. (Well, unless you enabled Cache To Disk, but you'd know if you'd done that)

Can you copy and paste the Loader node here, in code tags.

I'm not sure what you mean by that.

By the way, because the file ends in a number, Fusion thinks it's part of an image sequence. There's not any other files with the same name but a different number at the end? Eg "Skunk CA border 2.png" ? If so you might get that/those other file(s) on other frames.

Rename the file SkunkCABorder.png and make a new Loader to load it, to rule out that possibility.

I'm not sure what you mean by that.

Select the Loader node, hit copy, come to the forum, press the Code button you see above the text entry box then between the code open and close tags, hit paste to paste in the Loader node Lua code.

There's not any other files with the same name but a different number at the end?

FFFFffffff..... There certainly are. Of course I should have known better than to add a number to the end of a file I made multiple versions of! I mean, I'm probably the first person to need multiple variations of the same file, and in hindsight, tacking a number onto the end of the filenames as a way to distinguish between them is clearly something no one else would be foolish enough to even consider... (Genuinely having a laugh and not trying to be rude, but seriously, how could I possibly have assumed that would be an issue?)

Here's the loader node in case that's still relevant:

Code: Select all

{
   Tools = ordered() {
      Loader2SkunkCAborder1png = Loader {
         Clips = {
            Clip {
               ID = "Clip1",
               Filename = "C:\\Users\\Cody\\Desktop\\SN keys\\Skunk CA border 01.png",
               FormatID = "PNGFormat",
               StartFrame = 1,
               Length = 2,
               LengthSetManually = true,
               TrimIn = 0,
               TrimOut = 1,
               ExtendFirst = 0,
               ExtendLast = 1288,
               Loop = 1,
               AspectMode = 0,
               Depth = 0,
               TimeCode = 0,
               GlobalStart = 0,
               GlobalEnd = 1289
            }
         },
         CtrlWZoom = false,
         NameSet = true,
         Inputs = {
            ["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2" }, },
            ["Clip1.PNGFormat.PostMultiply"] = Input { Value = 1, },
         },
         ViewInfo = OperatorInfo { Pos = { 838.842, 495.429 } },
      }
   },
   ActiveTool = "Loader2SkunkCAborder1png"
}

Just to understand this further though, the behavior I'm seeing is because it's loading up the one ending in 01 instead of 02 because it thinks it should start at the beginning of what it's assuming is a sequence of images?

So that was it?

If you're asking how you could have spotted it, there's a couple of indications in the Loader:


You would also only see the Loader on the exact frames indicated by the frames on disk, eg frames 1 and 2, so I'm guessing you then manually dragged the Global In/Out to make it viewable on the whole range? Which automatically adjusted the Hold Last Frame to make it repeat the last frame over and over, which I see in the Loader you've copied here.

I'm guessing you then manually dragged the Global In/Out to make it viewable on the whole range?

...yep