Mini 3 Pro had lossless digital zoom in video. Mini 4 Pro doesn't seem to have this?

[fuzzybabybunny]

Taken from this thread:

Confirmed: Digital zoom is LOSSLESS for video!

I've been relentlessly searching the internet, trying to discover if digital zoom could indeed be lossless. I found nothing about it. So, after thorough testing myself, with a resolution chart, I can confirm that it is—up to 2x! Please note, this discovery pertains to video ONLY, not still...

forum.dji.com

I tested this on the Mini 4 Pro and the 2x digital zoom is obviously less detailed in video.

Can anyone confirm this finding? I thought that both drones used the same sensor?

 

[Dave Maine]

Digital zoom by definition is not losssless. It is simply a crop which deletes surrounding pixels.

 

[fuzzybabybunny]

Digital zoom by definition is not losssless. It is simply a crop which deletes surrounding pixels.

Not necessarily on high resolution sensors. Depends on how the digital zoom is implemented.

Lossless or near-lossless digital zoom is achievable and the Mini 4 Pro already does it for photos shot in 12MP mode.

 

[Droning on and on...]

Digital zoom by definition is not losssless. It is simply a crop which deletes surrounding pixels.

Which is lossless if the sensor has greater resolution than the output.

At 8064x6048, ¼ of the sensor area is full resolution 4K video. The center 3840x2160 pixel area can be cropped effectively producing 2x magnification without loss of resolution.

In fact, the image processor must decimate the full 8k image down to 4k at 1x zoom, tossing image data.

If shooting in FHD the image can be digitally zoomed up to 4x without losing resolution. No pixels are being blown up to cover several pixels in the output image.

 

[tlyons]

Which is lossless if the sensor has greater resolution than the output.

At 8064x6048, ¼ of the sensor area is full resolution 4K video. The center 3840x2160 pixel area can be cropped effectively producing 2x magnification without loss of resolution.

In fact, the image processor must decimate the full 8k image down to 4k at 1x zoom, tossing image data.

If shooting in FHD the image can be digitally zoomed up to 4x without losing resolution. No pixels are being blown up to cover several pixels in the output image.

Do you know of any DJI documentation on that? Or gotten good results? I also had thought the Mini 3 Pro has lossless zoom but any time I have used it turns out like this hot mess:

I haven't used it much since the results were so poor.

 

[akdrone]

So much of these disagreements come down to semantics and what "digital zoom". For most folks I think the term means when you have a 4K sensor and you use a "zoom" setting so you can look at some portion of that sensor and enlarge it to fill the entire screen. There is always loss of definition in that case and I think that is all the Mini3 can do. Some cameras - I don't know to what degree DJI implements this - will use some algorithms to sharpen and enhance an image/clip that has been created by this method. That can indeed be helpful. I am pretty sure (not 100%) that iPhones and other smartphones often use this technical wizardry. I've not heard that is the case with DJI. Does anyone know?

 

[davidarmenb]

The 48MP sensors on these drones use what’s called a QuadBayer filter array, as opposed to the Traditional Bayer array. Because of this, it is able to combine four pixels into one using what is called pixel-binning. It uses this method to achieve 12MP photos even though the sensor itself has ~48 million physical photodiodes.

Lossless digital zoom, where you are fluidly zooming in from 1x to 2x, will never be possible with current sensor technology. The only way to implement “lossless” digital zoom is if the sensor has a QuadBayer Array and the “zoom” jumps from 1x (using 4-to-1 pixel binning) to 2x (using just the central ~4000x3000 photodiodes without pixel binning). However, this will still not be completely lossless because interpolating a transitional Bayer Array from a QuadBayer array using array conversion will create some slight color artifacts (unnoticeable to most) and more noise. But it will be almost lossless. This same method can be used for video with 48MP QuadBayer sensors, if the manufacturer implemented it, and if you are recording in 1080p. None of the DJI drones implement this type of digital zoom as far as I am aware.

On the other hand, one can shoot video in 4K and make their production resolution 1080p, which will give them the ability to fluidly zoom all the way to 2x in post (cropping) while not losing any detail because 4K cropped to 2x is 1080p.

On a side note, the QuadBayer color filter array in the Mini 4 Pro is also how one is able to choose between 12MP and 48MP photo capture. When using 12MP photo mode, the 48MP sensor uses 4-to-1 pixel binning to create 12 million huge photodiodes by combining every four photodiodes (2x2) into one big photodiode. When changing into 48MP photo mode, it uses each photodiode individually, but because it has a QuadBayer array, it needs to use array conversion to convert the QuadBayer to a Traditional Bayer, so 48MP photos have slightly more noise and very very slightly worse color rendering, which most people won’t notice at all.

Shooting video uses only 12MP mode so it also uses 4-to-1 pixel binning and then crops the 4:3 aspect ratio to 16:9.
I am not sure how it shoots 1080p but it is most likely using over-sampling to turn the source 4K data from the sensor into 1080p footage.

 

[akdrone]

The 48MP sensors on these drones use what’s called a QuadBayer filter array, as opposed to the Traditional Bayer array. Because of this, it is able to combine four pixels into one using what is called pixel-binning. It uses this method to achieve 12MP photos even though the sensor itself has ~48 million physical photodiodes.

Lossless digital zoom, where you are fluidly zooming in from 1x to 2x, will never be possible with current sensor technology. The only way to implement “lossless” digital zoom is if the sensor has a QuadBayer Array and the “zoom” jumps from 1x (using 4-to-1 pixel binning) to 2x (using just the central ~4000x3000 photodiodes without pixel binning). However, this will still not be completely lossless because interpolating a transitional Bayer Array from a QuadBayer array using array conversion will create some slight color artifacts (unnoticeable to most) and more noise. But it will be almost lossless. This same method can be used for video with 48MP QuadBayer sensors, if the manufacturer implemented it, and if you are recording in 1080p. None of the DJI drones implement this type of digital zoom as far as I am aware.

On the other hand, one can shoot video in 4K and make their production resolution 1080p, which will give them the ability to fluidly zoom all the way to 2x in post (cropping) while not losing any detail because 4K cropped to 2x is 1080p.

On a side note, the QuadBayer color filter array in the Mini 4 Pro is also how one is able to choose between 12MP and 48MP photo capture. When using 12MP photo mode, the 48MP sensor uses 4-to-1 pixel binning to create 12 million huge photodiodes by combining every four photodiodes (2x2) into one big photodiode. When changing into 48MP photo mode, it uses each photodiode individually, but because it has a QuadBayer array, it needs to use array conversion to convert the QuadBayer to a Traditional Bayer, so 48MP photos have slightly more noise and very very slightly worse color rendering, which most people won’t notice at all.

Shooting video uses only 12MP mode so it also uses 4-to-1 pixel binning and then crops the 4:3 aspect ratio to 16:9.
I am not sure how it shoots 1080p but it is most likely using over-sampling to turn the source 4K data from the sensor into 1080p footage.

View attachment 174183

That was an excellent summation.

 

[Droning on and on...]

In 12MP mode, the sensor captures 4032×3024. At 1080P, this is sufficient to zoom by cropping to the center 1920×1080 pixels without losing resolution.

With no zoom, the entire sensor image is being decimated (i.e. reduced in resolution) to 1920×1080.

When using the zoom feature in 1080p, there isn't any good reason to take the full sensor, decimated image at 1920×1080, crop out the center 960×540 pixels, then using something like bicubic to blow it back up again to 1980×1080, now at half the linear resolution (quarter of the pixels) of the actual sensor.

I don't know, but I don't believe DJI is this stupid. But they could be, I suppose.

 

[rickmurray1989]

Taken from this thread:

Confirmed: Digital zoom is LOSSLESS for video!

I've been relentlessly searching the internet, trying to discover if digital zoom could indeed be lossless. I found nothing about it. So, after thorough testing myself, with a resolution chart, I can confirm that it is—up to 2x! Please note, this discovery pertains to video ONLY, not still...

forum.dji.com

I tested this on the Mini 4 Pro and the 2x digital zoom is obviously less detailed in video.

Can anyone confirm this finding? I thought that both drones used the same sensor?

The zoomed video is based upon electronic zooming, not optical. Neither support lossless video nor still zooms.

 

[FASTFJR]

The zoomed video is based upon electronic zooming, not optical. Neither support lossless video nor still zooms.

BINGO... Digital zoom is kind of comical

 

[Droning on and on...]

The zoomed video is based upon electronic zooming, not optical. Neither support lossless video nor still zooms.

BINGO... Digital zoom is kind of comical

See post #9.