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The truth is that when people test out filters they are looking close up at the pixels, trying to squeeze out detail, but the reality is that whatever minute de

The truth is that when people test out filters they are looking close up at the pixels, trying to squeeze out detail, but the reality is that whatever minute detail might get slightly softened by a 2.2-2.5 gauss filter will get chewed up by the process of color correction and compression anyway. The aliasing you can end up with from a mitchell filter though can be noticeable all through the process. Not only that, but what will the compositor do when they see the aliasing? They'll blur it. Basically it is trying to squeeze blood from a stone and the image out of renderer is going to be far sharper than anyone will see because it will go through multiple stages. Even compositing almost never leaves a render verbatim. There is usually some sort of slight softening, chromatic aberration, lens distortion and/or other transforms that require resampling anyway. It is picking up pennies in front of a bulldozer and only causes problems to have a filter that's too sharp, let alone one that has negative lobes.

dahart 2y ago
Oh FWIW, the sessions I remember most vividly were for the first Shrek movie, which was printed to actual film, projected to a theater screen, and final render was at slightly lower than 1080p resolution. The digitizing to film does add a little blur, of course, but not a lot since the resolution was so low and the pixels so big. The filter did kinda matter, and the compositors did not add extra blur in this case. I was highly impressed with how sensitive the director and lighting/fx supes were to filter differences, and how quickly they could spot them in animated clips that were often less than one second long. The main thing they were doing was trying to avoid texture sizzle without overblurring.
- CyberDildonics 2y ago
  The digitizing to film Scanning film would be digitizing it, going out to film could be called printing. does add a little blur A lot of blur. 35mm film had a lot of folk wisdom built up around it and even though it would be scanned and worked on at 2k resolution for live action vfx, if you actually zoomed in it would be extremely soft. You could get away with 1.5k just for printing to the first generation film, let alone the 2nd gen master prints and the third gen prints that went out to theaters. The filter did kinda matter It is extremely unlikely lighters were changing the actual pixel sample filters on a shot by shot basis. This is something that is set globally. Also if you set it differently for different passes and you use holdouts, your CG will not line up with the other CG renders and you will get edges from the compositing algebra not being exact. I was highly impressed with how sensitive the director and lighting/fx supes were to filter differences, No one is changing the pixel sampling filters on a shot by shot basis and no one is going to be able to tell the filter just by looking at playing back on film. This is simply not reality. and how quickly they could spot them in animated clips that were often less than one second long Absolutely not. Whatever you are talking about is not different pixel sample filters. Aliasing in general yes, but that's much more complex. The main thing they were doing was trying to avoid texture sizzle without overblurring. This has nothing to do with the renderer's pixel sample filters which is what would be the only analog to the article here. Maybe you are talking about texture filtering, although that is not a difficult problem due to mipmapping and summed area mapping. Even back then a geforce 2 could do great texture filtering in real time. Maybe you are talking about large filter sizes in shadow maps, which need a lot of samples when using percentage closer filtering, but that has nothing to do with this.
  - dahart 2y ago
    Whoa what’s with the totally confrontational argumentative stance?!? I’m very confused by your reply. I thought we were having a nice conversation about filtering. Lighters on Shrek were indeed not changing the pixel filter shot by shot. We did, however, multiple times, sit down to evaluate and compare various pixel filters built into the renderer, and when we did that, the pixel filter actually was changed for every shot, so they could be compared. The filter mattered because it was set globally, and because the resolution was low, less than 1k pixels vertically. That is precisely why we spent time making sure we were using the filter we wanted. I am in fact talking about different pixel filters, and the director and supes could tell the difference in short animated clips scanned to film, which is why it was so impressive to me. If you don’t believe me, I can only say that reflects on your experience and assumptions and not mine. Both subtle high frequency sizzle as well as other symptoms of aliasing do occur when the pixel filter is slightly too sharp. I don’t know why you’re arguing that, but you seem to be making some bad assumptions.
    - CyberDildonics 2y ago
      Whoa what’s with the totally confrontational argumentative stance?!? Someone correcting you isn't victimizing you. I’m very confused by your reply. That's fine, I'll explain it again. We did, however, multiple times, sit down to evaluate and compare various pixel filters built into the renderer, Makes sense, this is initial set up. because the resolution was low, less than 1k pixels vertically. Resolution isn't referred to by the vertical resolution in shorthand. 2k usually means around 2,000 pixels or more horizontally. The vertical resolution is mostly dependent on what crop of the 35mm negative is being used which dictates aspect ratio. You said things like "low resolution, 1080p" which aside from mostly being used for HD video, is actually close to 2k resolution (1920x1080). The reason this is important is that when I said 1.5k is still sharper than film I'm talking about a 25% step down in resolution still needing to be softened to fit in with 35mm photography. Here is the really relevant part - this is mostly about edge anti-aliasing and possibly motion blur. and the director and supes could tell the difference in short animated clips scanned to film, which is why it was so impressive to me. If you don’t believe me, I can only say that reflects on your experience and assumptions and not mine. If there are clips meant to compare filters and they are being told what they are looking at this makes sense. If you are saying that they would look at a clip on film and say what pixel filter was being used, it's just not true. It's gone through too many stages and it's not something anyone cares about once it's locked down. It's too soft and pixel filters are too similar to each other. It's like someone drinking a long island iced tea and saying they can taste where the water in the cola came from. Both subtle high frequency sizzle as well as other symptoms of aliasing do occur when the pixel filter is slightly too sharp. I don’t know why you’re arguing that, but you seem to be making some bad assumptions. I already said this up top, but I don't think you're understanding what I've been saying all along, which is that the sharpness from something other than gauss isn't worth the trouble and whatever super minor and subtle softness is there is irrelevant because it's overshadowed through the rest of the process. What you're saying here doesn't seem like you are talking about pixel filtering. Aliasing on the edges is the easiest aliasing to deal with because it doesn't take many samples. Dealing with it with pixel filters is basically the same as blur, which isn't really a way to confront it at all. Before you were talking about texture aliasing and now you're talking about "high frequency sizzle" and if this was anywhere except the edges of the CG, it wasn't people talking about pixel filters that are being discussed here, it was texture or shadow map filtering. I'm sure you saw and learned a lot, but this is a very specific context and part of rendering which is arguably one of the easiest parts to set and move on. It's much more likely what you saw was people dealing with difficult aliasing problems through other means that wouldn't blur the entire image. I'll say my overall point again though (which isn't exactly related to what you said) - CG goes through a lot of stages that affect the image much more than the pixel filter, so it is not wise to use something with negative lobes to get very slight sharpness at one stage when it is all downsides with no upsides when looking at the entire pipeline.
a_e_k 2y ago
> Basically it is trying to squeeze blood from a stone and the image out of renderer is going to be far sharper than anyone will see because it will go through multiple stages. Even compositing almost never leaves a render verbatim. Don't forget that these days, it's all going through some ML-based denoiser, anyway. I wouldn't be surprised if filter choice is nearly irrelevant at this point (except for training).

dahart 2y ago

Oh FWIW, the sessions I remember most vividly were for the first Shrek movie, which was printed to actual film, projected to a theater screen, and final render was at slightly lower than 1080p resolution. The digitizing to film does add a little blur, of course, but not a lot since the resolution was so low and the pixels so big. The filter did kinda matter, and the compositors did not add extra blur in this case. I was highly impressed with how sensitive the director and lighting/fx supes were to filter differences, and how quickly they could spot them in animated clips that were often less than one second long. The main thing they were doing was trying to avoid texture sizzle without overblurring.

CyberDildonics 2y ago
The digitizing to film Scanning film would be digitizing it, going out to film could be called printing. does add a little blur A lot of blur. 35mm film had a lot of folk wisdom built up around it and even though it would be scanned and worked on at 2k resolution for live action vfx, if you actually zoomed in it would be extremely soft. You could get away with 1.5k just for printing to the first generation film, let alone the 2nd gen master prints and the third gen prints that went out to theaters. The filter did kinda matter It is extremely unlikely lighters were changing the actual pixel sample filters on a shot by shot basis. This is something that is set globally. Also if you set it differently for different passes and you use holdouts, your CG will not line up with the other CG renders and you will get edges from the compositing algebra not being exact. I was highly impressed with how sensitive the director and lighting/fx supes were to filter differences, No one is changing the pixel sampling filters on a shot by shot basis and no one is going to be able to tell the filter just by looking at playing back on film. This is simply not reality. and how quickly they could spot them in animated clips that were often less than one second long Absolutely not. Whatever you are talking about is not different pixel sample filters. Aliasing in general yes, but that's much more complex. The main thing they were doing was trying to avoid texture sizzle without overblurring. This has nothing to do with the renderer's pixel sample filters which is what would be the only analog to the article here. Maybe you are talking about texture filtering, although that is not a difficult problem due to mipmapping and summed area mapping. Even back then a geforce 2 could do great texture filtering in real time. Maybe you are talking about large filter sizes in shadow maps, which need a lot of samples when using percentage closer filtering, but that has nothing to do with this.
- dahart 2y ago
  Whoa what’s with the totally confrontational argumentative stance?!? I’m very confused by your reply. I thought we were having a nice conversation about filtering. Lighters on Shrek were indeed not changing the pixel filter shot by shot. We did, however, multiple times, sit down to evaluate and compare various pixel filters built into the renderer, and when we did that, the pixel filter actually was changed for every shot, so they could be compared. The filter mattered because it was set globally, and because the resolution was low, less than 1k pixels vertically. That is precisely why we spent time making sure we were using the filter we wanted. I am in fact talking about different pixel filters, and the director and supes could tell the difference in short animated clips scanned to film, which is why it was so impressive to me. If you don’t believe me, I can only say that reflects on your experience and assumptions and not mine. Both subtle high frequency sizzle as well as other symptoms of aliasing do occur when the pixel filter is slightly too sharp. I don’t know why you’re arguing that, but you seem to be making some bad assumptions.
  - CyberDildonics 2y ago
    Whoa what’s with the totally confrontational argumentative stance?!? Someone correcting you isn't victimizing you. I’m very confused by your reply. That's fine, I'll explain it again. We did, however, multiple times, sit down to evaluate and compare various pixel filters built into the renderer, Makes sense, this is initial set up. because the resolution was low, less than 1k pixels vertically. Resolution isn't referred to by the vertical resolution in shorthand. 2k usually means around 2,000 pixels or more horizontally. The vertical resolution is mostly dependent on what crop of the 35mm negative is being used which dictates aspect ratio. You said things like "low resolution, 1080p" which aside from mostly being used for HD video, is actually close to 2k resolution (1920x1080). The reason this is important is that when I said 1.5k is still sharper than film I'm talking about a 25% step down in resolution still needing to be softened to fit in with 35mm photography. Here is the really relevant part - this is mostly about edge anti-aliasing and possibly motion blur. and the director and supes could tell the difference in short animated clips scanned to film, which is why it was so impressive to me. If you don’t believe me, I can only say that reflects on your experience and assumptions and not mine. If there are clips meant to compare filters and they are being told what they are looking at this makes sense. If you are saying that they would look at a clip on film and say what pixel filter was being used, it's just not true. It's gone through too many stages and it's not something anyone cares about once it's locked down. It's too soft and pixel filters are too similar to each other. It's like someone drinking a long island iced tea and saying they can taste where the water in the cola came from. Both subtle high frequency sizzle as well as other symptoms of aliasing do occur when the pixel filter is slightly too sharp. I don’t know why you’re arguing that, but you seem to be making some bad assumptions. I already said this up top, but I don't think you're understanding what I've been saying all along, which is that the sharpness from something other than gauss isn't worth the trouble and whatever super minor and subtle softness is there is irrelevant because it's overshadowed through the rest of the process. What you're saying here doesn't seem like you are talking about pixel filtering. Aliasing on the edges is the easiest aliasing to deal with because it doesn't take many samples. Dealing with it with pixel filters is basically the same as blur, which isn't really a way to confront it at all. Before you were talking about texture aliasing and now you're talking about "high frequency sizzle" and if this was anywhere except the edges of the CG, it wasn't people talking about pixel filters that are being discussed here, it was texture or shadow map filtering. I'm sure you saw and learned a lot, but this is a very specific context and part of rendering which is arguably one of the easiest parts to set and move on. It's much more likely what you saw was people dealing with difficult aliasing problems through other means that wouldn't blur the entire image. I'll say my overall point again though (which isn't exactly related to what you said) - CG goes through a lot of stages that affect the image much more than the pixel filter, so it is not wise to use something with negative lobes to get very slight sharpness at one stage when it is all downsides with no upsides when looking at the entire pipeline.

a_e_k 2y ago

> Basically it is trying to squeeze blood from a stone and the image out of renderer is going to be far sharper than anyone will see because it will go through multiple stages. Even compositing almost never leaves a render verbatim. Don't forget that these days, it's all going through some ML-based denoiser, anyway. I wouldn't be surprised if filter choice is nearly irrelevant at this point (except for training).