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Sorry. Didn't mean to hijack the thread. Just trying to give a friendly reminder that resolution is integral to color depth. On the other hand, there certainly is nothing "geeky" about a thread titled, "Is 4K Not as Important as We Think It Is?" :) I don't think that there is anything inherently wrong with 4K (or with any other given resolution). Of course, the higher the resolution, the greater the bandwidth/resource requirements (all other variables remaining the same). In addition, those DPs stressed lighting over technical specs (including dynamic range and "color science"). YouTube looks awful on a lot of monitors. However, the moire problem could be peculiar to your set-up. What is the resolution of your monitor? That's an interesting topic. Just the other day, I was talking to my Indian filmmaker friend, and he explained that the reason why a lot of Indian films were completely looped (other than practical shooting advantages) was that Indian audiences like the "other-worldly" feel of overdubbed dialog. I don't think that 4K is particularly "exciting." 4K cinema cameras have been around since the first Dalsa Origin (2002?). 4K is yet another step in the cinematography megapixel race -- a conspicuous technical spec for producers (and others) to demand. In regards to the notion that dynamic range and color are more important than resolution, again, resolution is integral to color depth. However, a system with 10-bit depth and at least HD resolution would certainly suffice for a lot of the work done today. As I said earlier in the thread, I would rather shoot HD with a Sony F35 than 5K with a RED Epic. As those DPs suggested, lighting usually trumps all of the technical specs.

No. >I started a thread for members to post on how they dealt with the banding in the A7s. I already knew why banding is prevalent in the A7s -- it's 8-bit. Not by anyone who knows the difference between bit depth and dynamic range. Bit depth and dynamic range are two completely independent properties. Not necessarily. Banding is the phenomenon of a value threshold transition that falls within a broad smooth, tonal gradation. It is more of a result of bit depth and the smoothness of tonal transitions in the subject. Other 8-bit cameras exhibit the same (or more) banding as the A7s, and most of those other cameras have less dynamic range. For instance, the A7s has a large capture dynamic range with value thresholds that are spaced far apart in amplitude. So, the A7s might have one value threshold that falls within in a sky that ranges, say, 1/16th of a stop, while an 8-bit camera with less dynamic range might have 3 value thresholds that fall within the same sky. In such a scenario, the A7s has two bands in the sky, while the other 8-bit camera has four bands in the sky (and probably more contrast!). The smoother the gradation of intensity, the greater the chance of banding. Yes, higher bit depth can make banding less noticeable. Not by those who know the difference between bit depth and dynamic range. Bit depth and dynamic range are two completely independent properties. Bit depth and dynamic range are two completely independent properties. What can one say, except don't believe everything that you read on Wikipedia. The fact is that a 4-bit digital system can have over thirty stops of dynamic range, while a 16-bit system can have only one "stop" of dynamic range. Furthermore, analog systems (which have zero bit depth) can have a dynamic range of over thirty "stops." Put simply, bit depth is the potential number of value increments within a digital system. Dynamic range is the ratio between the largest and smallest values of usable amplitude, in both analog and digital systems.

Okay. What is the meaning of this statement? Given enough resolution and barring noise, a 1-bit camera could certainly provide the same amount of color info as an Alexa 65. Forget the summing -- summing implies that we are using more than 1-bit in our system (after the summing), and summing is completely unnecessary. I edited-out the summing step just before your response. In regards to the "loss of info" -- to what are you referring? Given infinite resolution and barring any other practical problems (such as noise), our 1-bit camera could certainly have more color info than an Alexa 65. The subject/scene that you are shooting with the 1-bit camera has resolution down to the atomic level. One could start with an analog image that has 0-bit depth. Regardless of the original bit depth and resolution (or color depth), the image is rendered within the color depth limits of the printing system. Thanks for reminding me of Velox. Not necessarily -- not if the printing system is higher quality than that of the original image. If the original image was shot on Royal-X and the printing screen is 10x finer than the Royal-X grains, there could be is no essential loss in quality -- even though the final image is not exactly the same as the original. The same principle applies to transcoding video. I fail to see how the fundamental relationship between resolution, bit depth and color depth causes misunderstanding, since most are completely ignorant of that actual relationship. Dynamic range and bit depth are two completely different and independent properties. By the way, dynamic range also exists in analog systems, but bit depth exists ONLY in digital systems

Bit depth and dynamic range are two completely independent and unrelated properties. One can map various bit depth ranges to any section of the amplitude range. Dynamic range refers to the "usable" section of the amplitude range. That's not how a 1-bit camera would be configured. With such a low bit-rate camera, one would have to create pixel groups with a range of sensitivities among the pixels in each group. There are four basic ways to vary the sensitivities of adjacent pixels: 1. electronically; 2. with optical filtration (similar to that of RGB filters on pixel groups, but with ND instead); 3. with different sized apertures (or obstructions) in front of each pixel in the group; 4. with various sized pixels. I think that some early digital imaging experimenters tried an electronic cascading technique with CCDs to get a greater range of tones, and Magic Lantern's "Dual ISO" feature can change pixel sensitivity on a per-line basis. Also, I am fairly sure that Panavision was using either varied pixel NDs or varied pixel apertures with their original Dynamax HDR sensor -- a true example of getting greater tonal range by increasing resolution with a fixed bit depth. In addition, Fuji is currently using various pixel sizes on their X-Tran sensor (for moire/aliasing elimination -- not for increased tonal range). I am not sure if screen capture/printing is considered to be an actual dithering process. Huh? How are you "harping?"

Sorry to harp on this point, but resolution is fundamental to color science. Resolution influences color depth just as much as bit depth influences color depth. Yes, bit depth is not the same thing as color depth -- they are decidedly different properties. Essentially, bit depth is the potential of color information in one digital pixel, whereas color depth (in digital imaging) is the total potential of color information from a given group of pixels. That "given group of pixels" involves the resolution side of the equation. By the way, color depth also applies to analog imaging -- bit depth only applies to digital imaging. Resolution is so crucial to color depth that a 1-bit image can exhibit an amazing range of photographic tones and colors, given enough resolution. In fact, every day we see what are essentially 1-bit images, when we look at printed magazines, newspapers and many posters and billboards. Misconceptions abound regarding the basics of color depth and how it relates to resolution, so much so that it is doubtful that any one of these "cinematography dream team" experts is aware of these color fundamentals. Agreed, and, by the same token, "Gilligan's Island" would be just as funny on 4k as it is on SD. In addition, I certainly would rather shoot HD with a Sony F35 (or with a BMPCC and a speedbooster) than 5K with a Red Epic. 10-bit HD is enough color depth for most of my work, and the F35 (and the BMPCC) footage looks better to me than that from any of the Red cameras.

Good work on both videos! However, I don't see anything super special with the skin tones in the color video. It just looks like it was well exposed and nicely graded, with some interesting lighting in a couple of shots and with excellent moves/expressions from the models (which is 90% of the battle). High speed certainly helps with the "sexiness" of the feel. In regards to the brief black & white video, it looks like there could be reduced red channel and/or boosted green (and possibly blue) channel in the B&W conversion. Gotta be careful with such a technique, because, although it can darken skin in a nice way and make blue forearm veins disappear, subtracting red and/or boosting green gives more contrast to red blemishes. Boosting blue can also increase noise.

Great interview! Lots of good information. Thanks! As I understand, all of the Alexa XT models (XT, XT Plus, XT M and XT Studio) have 4:3 sensors. Furthermore, I think that there are a few 4k machine vision cameras that have 4:3 sensors.

The primary benefit of this practice is that the full color depth can be retained when converting to a lower resolution. Otherwise, color information is being discarded.

Actually, it does work and people have been doing it for years. You CAN sacrifice resolution for increased bit depth, with certain caveats: - banding in the original image won't automatically disappear with the increased bit depth; - the color depth can never be increased (bit depth is not color depth). This process was discussed extensively in >this thread.

Change the name of folder "/Users/TaJnB/Movies/untitled folder" to a name without any spaces (or special characters), such as: /Users/TaJnB/Movies/gh4files Make sure that the gh444 app and your gh4 mov files are in the directory /Users/TaJnB/Movies/gh4files Type at the terminal prompt: cd /Users/TaJnB/Movies/gh4files Press "enter" (or "return). The working directory of your terminal should now be "/Users/TaJnB/Movies/gh4files" Now, type at the terminal prompt: ./gh444 your_gh4_mov_file Replace "your_gh4_mov_file" with the actual name of your first gh4 mov file (it seems that you have to do each file one at a time). Press "enter" (or "return"). The gh444 app should now be converting your first gh4 mov file.

The problem is not the flange-focal distance, as Sony E-mount and Canon EOSM (EF-M) mounts have very short flange-focal distances (18mm), yet ASP-C sensors are offered with Canon EF-M mounts and full frame/ASP-C sensors are offered in E-mount. The flange-focal distance for micro 4/3 mount is longer than that of the EF-M mount and E-mount -- micro 4/3 is 19.25mm Indeed, there are plenty of E-mount focal reducers. Don't know how they work with APS-C sensors. My guess is that there would be some vignetting/softness in the corners of the frame. I seem to recall that someone posted some test shots in this forum a while back. Alas, there seems to be no focal reducers for the EF-M mount. So, I would guess that the problem is incorporating an optical element in the focal reducer that is large enough to fully cover ASP-C/Super-35 sensors.

I don't see a banded transition between bit-depth levels, nor do I see any "rainbowing." If it were an actual banded transition between bit-depth levels, the trasition would appear sharper, and we wouldn't see all that gradation within the area in question -- there would just be more bands instead of gradation. It looks like a cast shadow from the subject onto the background. The "banding" that you might perceive is probably the umbra and penumbra of the cast shadow. It appears that you were using a large, softer and cooler source (possibly daylight balanced) and that there was warmer ambient light (possibly tungsten balanced) filling the cast shadow.

@Inazuma Very interesting! I can see how the banding is reduced on the third clip (compared to the second clip). However, I confess that I prefer the contrast in the original clip over that in the processed clips. Thanks for the examples!

Looking forward to watching the video! If it is an easy process, I might reconsider shooting with the A7s. Thanks!

@Inazuma Thanks for the info! Thank you for linking the article. >One the comments shows the dramatic advantage of "diffuse" dithering over merely applying noise. I have used noise and blurring with still photos to eliminate banding, but with stills it is easy to localize the effect within the image. Has anyone used masks (or other selection tools) to keep blurring/noise/dithering to a local area in video?

What is the best way to deal with potential banding from the A7s and from other cameras that produce 8-bit files? Here is an example of banding that appeared in A7s footage after pushing it in post. Thanks!

I had to rethink my attitude towards artifacts (and artificiality) after seeing this video: http://www.youtube.com/watch?v=ugeVou06fWI

Not sure on this point. Exposure and "exposure range" are two different things. Also, exposure range and dynamic range are two different things. There is no universal correlation between bit-depth intervals and stops/luma/EV. Again, 8 bits worth of tones can be mapped to a system with a dynamic range of 25 stops, while 32 bits worth of tones can be mapped to a system with a dynamic range of only 5 stops. Indeed, cameras currently exist in which the user can select 8-bit, 12-bit, 16-bit and 24-bit depths, while camera's dynamic range remains unchanged. So, the value of each bit interval is determined by the dynamic range (or, usually, the amplitude range) of the digital system, along with the number of bits used. Of course, this scenario is fairly simple on linear response systems. Systems with adjusted response curves (or with randomly mapped intervals) are much more complex.

The rest of your post is excellent, but these two lines are not true. Bit depth and dynamic range are two different and independent properties. Bit depth is the number of tonal/amplitude steps in a digital system. Dynamic range gives the usable amplitude range relative to noise (similar to signal-to-noise ratio), and dynamic range applies to both digital and analog systems. To illustrate how bit depth and dynamic range are independent, consider that 8 bits of tonal intervals can be mapped to a system with a dynamic range of 25 stops, but, by the same token, 32 bits of tonal intervals can be mapped to a system with a dynamic range of 5 stops. Furthermore, a film emulsion (or analog magnetic tape) can have a dynamic range of, say, 7 stops, but that emulsion (or tape) will have no bit depth -- it's analog.

With a captured image, it is true that resolution can be sacrificed for increased bit depth -- folks have been doing it for years. On the other hand, the color depth of a captured image can never be increased (unless something artificial is introduced). It is important to keep in mind that bit depth and color depth are not the same property. The relationship of bit depth, resolution and color depth is fundamental to digital imaging. With all other variables remaining the same, the association between bit depth, resolution and color depth in an RGB system is: COLOR DEPTH = (BIT DEPTH x RESOLUTION)3 So, if two adjacent RGB pixel groups are cleanly summed/binned into one large RGB pixel group, the bit depth will double. However, the color depth will remain the same or be slightly reduced (depending on the efficiency of the conversion). The color depth can never increase. As others in this thread have suggested, there appears to be something else going on other than normal banding in the OP's first image. Even so, if banding exists in an image, increasing the bit depth at the cost of resolution will not eliminate the banding, unless the banding is only a few pixels wide (or unless the resolution becomes so coarse that the image is no longer discernable). Again, when swapping resolution for more bit depth, the bit depth has been increased, but not the color depth.

Well, that quote says it all (except for the fact that circle-of-confusion and depth-of-field are actually two different {but related} properties). Nowhere in that quote is resolution mentioned. Image format is mentioned as "often associated" with circle-of-confusion values, but the quote states that the most appropriate basis of circle-of-confusion is visual acuity. Visual acuity is not resolution. If we were to base depth-of-field on resolution, we would encounter all kinds of silly, varying DOF ratings of the same optical system, which would change with each film stock/sensor and with the whim of any person viewing the captured image who decides to manipulate it long after it has been captured.

That "free parameter" is determined by a fraction of the focal length, not by sensor/film resolution.

No. Post-capture processing and the "acceptable circle of confusion" don't affect the depth-of-field. Depth-of-field is an optical property that exists regardless of whether or not the image is captured. I seem to recall reading a similar point somewhere in this thread.

When discussing depth-of-field in the "real world," the term applies only to real world optical systems. No. Re-read the "simplifications." All of those post-capture processes are ignored by the DOF formulas. Depth-of-field is an optical property -- it has nothing to do with sharpening or softening an image after the image is received by the sensor/film. Furthermore, not all of the methods that you mentioned change the resolution. Full-frame, half-frame, 16mm, IMAX, 4"x5", 11"x14" -- the size of the medium at the focal plane really has nothing to do with the depth-of-field. Depth-of-field and an image's "look" are two different things, but, certainly, DOF can affect the "look" of an image. Well, this passage that you have quoted says it all: Resolution of the imaging medium is ignored. When the resolution of the capture medium is similar (or greater than) the optical resolution, the captured image will seem more blurred throughout, making it more difficult to discern the depth-of-field. Nevertheless, the depth-of-field (an optical property) remains the same. "Acceptable circle of confusion" and DOF are two different properties. Magnification of the image at the film plane affects resolution, but not depth-of-field. Cropping into and enlarging a captured digital image can lower the effective resolution, but manipulating a captured image has absolutely nothing to do with depth-of-field. I doubt that you would notice any difference in DOF with the same f-stop on the same lens, by merely changing film stocks. Regardless, you weren't increasing the depth-of-field -- you might have been creating an image that had a coarser resolution overall, thus, making the overall image look softer and more homogeneously in the same focus. Big sensors matter, but the size of the sensor doesn't change the DOF. Depth-of-field is an optical property.

No. I do not wish to get into a semantics argument, but the definitions of depth-of-field and circle-of-confusion involve basic, well-established optical properties that apply to imaging. The resolution of the sensor/film (and projector/monitor) is not a consideration, as depth-of-field is a purely optical characteristic. The Wikipedia page on depth-of-field addresses this very point (note limitation #6). No need to get personal, but you would be mistaken if you considered sensor/film resolution as an optical property. The term "Softer" is generic. It can apply to the properties of both resolution and sharpness. I never stated that you wrote so. The focal plane/surface is part of the optical system, but the resolution of the medium at the focal plane/surface has nothing to do with optics. Huh? I am not sure what you are proposing, but it appears that you are suggesting that the depth-of-field will change if I merely vary the ISO setting on my camera while the lens and its aperture remain the same. Is that what you are saying? If so, would you be interested in a little wager?