Digital 2x and 4x extender

BrianOdell wrote:

I see that the R50 has a “digital 2x and 4x extender” feature built in. I believe that the R6 ii also has this. Canon states that this is not simply a crop, and retains quality (jpeg only). How useful is this feature? Wondering how the R50 will work with the RF 100-400 and possibly a digital 2x or 4x extender?

"Retains quality" is a semantic trick, not an imaging one.  By "retains quality", they mean the number of pixels in the output file remains the same as if you didn't engage the digitial TC.  It does not mean, however, that each of these pixels has unique information like when you don't use this feature.  It's just like you cropped and then upsampled the image, before converting it to JPEG.

The only IQ "plus" here is that if you were shooting JPEG anyway, and not raw, then there may be a slight improvement in color resolution when you use this mode, because JPEGs cut color resolution in half, but if the digital TC upsampled it first then less would be lost.  However, color resolution is already lower than luminance resolution in Bayer cameras, so the typical loss from JPEG without a digital TC isn't all that great to begin with.

OK, one more "plus" might be that if you just distributed copies of a non-digital-TC image they could be subject to arbitrary bad resampling methods like nearest neighbor, but upsampling the images first reduces the artifacts from bad resampling methods like nearest neighbor.

Of course, anyone shooting raw can do all this in software without the digital TC.  the main benefit of a digital TC TC is the relevance of what you are looking at in the viewfinder, and what the camera is looking at for focus and metering, but I would prefer to have these as crop modes with raw files; not as a digital TC with JPEGs.

PicPocket wrote:

BrianOdell wrote:

Canon states that this is not simply a crop, and retains quality (jpeg only).

I wonder what that means. Free pixels? Retains 50% quality? JPEG only, so some processing trick. I wonder if that can mean crop and upscale as best as we can

That statement is as subjective as it gets it, unless there is some more detail there

Some people have suggested some kind of AI upsizing, but at the speed that these images can be burst at, it doesn't seem likely that there can be any kind of real "intelligence".  At best, there may be some kind of interpolation and sharpening that can estimate where edges are and place them at a higher resolution than the original.  A test would be to intentionally create jaggies with a very sharp lens, and a high-contrast B&W line at a slight angle to the perpendicular or horizontal and see if they step in single lines or in multiple lines.  If the digital TC does this with lines wider than one pixel in the output file, then it isn't doing anything but upsampling.

I had this on my Pany G9s. It gave me jpegs at MFT 20 meg rez. IQ took a hit - call it good cell phone grade.

I played with it a couple of times but never used it for serious stuff. It was fun trying to hand hold at 3200mm. I had an extra button so I set it for the digital zoom. Figured if I ever saw Bigfoot I was ready to go.

John Sheehy wrote:

BrianOdell wrote:

I see that the R50 has a “digital 2x and 4x extender” feature built in. I believe that the R6 ii also has this. Canon states that this is not simply a crop, and retains quality (jpeg only). How useful is this feature? Wondering how the R50 will work with the RF 100-400 and possibly a digital 2x or 4x extender?

"Retains quality" is a semantic trick, not an imaging one. By "retains quality", they mean the number of pixels in the output file remains the same as if you didn't engage the digitial TC. It does not mean, however, that each of these pixels has unique information like when you don't use this feature. It's just like you cropped and then upsampled the image, before converting it to JPEG.

Do you know what it is actually doing?

The only IQ "plus" here is that if you were shooting JPEG anyway, and not raw, then there may be a slight improvement in color resolution when you use this mode, because JPEGs cut color resolution in half, but if the digital TC upsampled it first then less would be lost. However, color resolution is already lower than luminance resolution in Bayer cameras, so the typical loss from JPEG without a digital TC isn't all that great to begin with.

OK, one more "plus" might be that if you just distributed copies of a non-digital-TC image they could be subject to arbitrary bad resampling methods like nearest neighbor, but upsampling the images first reduces the artifacts from bad resampling methods like nearest neighbor.

Of course, anyone shooting raw can do all this in software without the digital TC. the main benefit of a digital TC TC is the relevance of what you are looking at in the viewfinder, and what the camera is looking at for focus and metering, but I would prefer to have these as crop modes with raw files; not as a digital TC with JPEGs.

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Beware of correct answers to wrong questions.
John
http://www.pbase.com/image/55384958.jpg

PicPocket wrote:

BrianOdell wrote:

Canon states that this is not simply a crop, and retains quality (jpeg only).

I wonder what that means. Free pixels? Retains 50% quality? JPEG only, so some processing trick. I wonder if that can mean crop and upscale as best as we can

That statement is as subjective as it gets it, unless there is some more detail there

It's a bit of an odd one for sure. I had thought reading this that quite a few member are shooting with R6 II but this detailed isn't one I've seen folks list.

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PicPocket

chipman wrote:

I had this on my Pany G9s. It gave me jpegs at MFT 20 meg rez. IQ took a hit - call it good cell phone grade.

I played with it a couple of times but never used it for serious stuff. It was fun trying to hand hold at 3200mm. I had an extra button so I set it for the digital zoom. Figured if I ever saw Bigfoot I was ready to go.

There are certainly situations in which high magnification in the viewfinder is useful, but for anything that moves or that you have to find quickly, there is such a thing as TOO narrow, and cropping after the fact would be easier.

drsnoopy wrote:

If something sounds too good to be true, it almost certainly is. A 4x “digital TC” is only using one sixteenth of the sensor area, so that’s a 1.5MP image. When that is upscaled to 24MP, you’re not going to have “image quality retained”. It’s a trick, pure and simple, more suitable for smartphones than cameras. But then I guess that’s the target demographic.

Maybe it's trying to say this is an improvement over a 4x crop. I think it's that which is the comparison rather than with 4x FL.

drsnoopy wrote:

If something sounds too good to be true, it almost certainly is. A 4x “digital TC” is only using one sixteenth of the sensor area, so that’s a 1.5MP image. When that is upscaled to 24MP, you’re not going to have “image quality retained”. It’s a trick, pure and simple, more suitable for smartphones than cameras. But then I guess that’s the target demographic.

A less gimmicky thing to do is to just give more crop modes with raw output, perhaps with an option to upsample the results for JPEGs.

Beware of correct answers to wrong questions.
John
http://www.pbase.com/image/55384958.jpg

John Sheehy wrote:

drsnoopy wrote:

If something sounds too good to be true, it almost certainly is. A 4x “digital TC” is only using one sixteenth of the sensor area, so that’s a 1.5MP image. When that is upscaled to 24MP, you’re not going to have “image quality retained”. It’s a trick, pure and simple, more suitable for smartphones than cameras. But then I guess that’s the target demographic.

A less gimmicky thing to do is to just give more crop modes with raw output, perhaps with an option to upsample the results for JPEGs.

I think the word gimmick should be quantified John.

I did ask if you know how this works - I assume not.

Are you saying it isn't doing what it says?

Personally, being a devout engineer ensuring my teams follow a similar path I would like to understand what it is a really doing before drawing any conclusions.

I currently use AI upscaling in my workflow and wouldn't be without it. I also use (like it or not) across our mobile platforms.

Beware of correct answers to wrong questions.
John
http://www.pbase.com/image/55384958.jpg

koenkooi wrote:

Ephemeris wrote:

John Sheehy wrote:

drsnoopy wrote:

If something sounds too good to be true, it almost certainly is. A 4x “digital TC” is only using one sixteenth of the sensor area, so that’s a 1.5MP image. When that is upscaled to 24MP, you’re not going to have “image quality retained”. It’s a trick, pure and simple, more suitable for smartphones than cameras. But then I guess that’s the target demographic.

A less gimmicky thing to do is to just give more crop modes with raw output, perhaps with an option to upsample the results for JPEGs.

I think the word gimmick should be quantified John. [...]

For me: anything that lacks the option to save the RAW pictures it's based on is a gimmick.

That maybe your view but you haven't given requirements other than the word RAW. Given RAW isn't the same thing across cameras, brands and time I'm not sure the moving target is the best way to define something.

It should, in my opinion be a case of us it or is it not of use to someone. Somehow you would have to define your gimmick outside of those sets. If so then we would agree.

Afterall JPEGs are useful.

So:

• In-camera compositing for focus stacks: Not a gimmick, you can opt to keep the RAWs

Are all cameras doing this? I had thought some only output in JPEG. That would seem useful and thus not a gimmick.

• In-camera panorama mode: Gimmick, it doesn't even store the pictures as jpegs, you only get the result. Canon does have a list of recommended lenses: https://cam.start.canon/en/H001/supplement_0150.html

Do users / owners find it useful? I don't know but if they do then not gimmick.

• Digital TC: Gimmick, it isn't even available when the camera set is set to RAW only: https://cam.start.canon/en/C013/manual/html/UG-04_Shooting-1_0060.html

Do users / owners find it useful? I don't know but if so not a gimmick.

• Crop mode: Not a gimmick, you get to keep a much smaller RAW

If crop mode also exits in video modes, not all of those are RAW yet it is useful and therefore not a gimmick.

The digital TC mode would, for me, only be useful to turn the camera into a spotting scope for showing my kids things far away. I currently use the magnified view, but that is a bit of hassle since it involves switching the lens to MF. And I routinely forget to switch it back!

So maybe this is useful to you and therefore not a gimmick.

My question is how does it work? A simple system diagram would suffice. I am not interested in telling people if they should think it's a gimmick or not but if it is or isn't useful. Knowing the mechanism by which it functions may help to make it more useful.

I would also be convenient if you want to quickly send a a picture of something very far away to someone else. I bet the camera will do a better job at upscaling than the builtin photo app on your phone.

If I pull an image via Canon Connect to my phone can it be upscaled? Maybe you mean something else I was just curious as I don't think Abode offer this or Topaz so we may be able to leverage such a facility.

drsnoopy wrote:

Ephemeris wrote:

drsnoopy wrote:

If something sounds too good to be true, it almost certainly is. A 4x “digital TC” is only using one sixteenth of the sensor area, so that’s a 1.5MP image. When that is upscaled to 24MP, you’re not going to have “image quality retained”. It’s a trick, pure and simple, more suitable for smartphones than cameras. But then I guess that’s the target demographic.

Maybe it's trying to say this is an improvement over a 4x crop. I think it's that which is the comparison rather than with 4x FL.

Same thing, same issue. 4x crop is the same as 4x “digital teleconverter”. A 24MP R50 sensor with a 4x crop = 1.5 MP image.

The question: is it the same thing. They suggest it isn't the same.

So in camera zoom isn't the same as the equivalent crop after the fact.

So no, not the same.

skeudenn wrote:

it brings to mind the clear image zoom on sony e cameras

Do you know how that functions by any chance?