I’ve been playing and have come up with my first set of custom profiles for the Canon C300. You’ll find all the details here: http://www.xdcam-user.com/forum3/viewtopic.php?f=44&t=962 including a downloadable package that you can copy to an SD card and the load the files directly to your own C300.
You must be registered with the forum/blog to view the page, but registration is free and open to all. Any problems let me know.
The Profiles include:
AC-Neutral: a natural looking, true to life image.
AC-Vivid: A bright colourful and vivid image.
AC-3200a: Use this profile when shooting at ISO 3200 to maximise sensitivity and control noise.
AC-6400a: Use this profile when shooting at ISO 6400 to maximise sensitivity and control noise.
AC-Cine1: A neutral filmic looking image that can be used straight form the camera or graded.
I’ve added a new section in the xdcam-user.com forum for listing details of my various picture profiles. You will need to be a registered forum member to view or comment, but registration is free. I hope to add many profiles to this forum over the coming weeks for many of the XDCAM cameras as well as the new Canon C300 once I start to get that dialled in. I’ve started with my EX S-Log style gamma curve.
I promised I would re-visit some of my Picture Profile stuff. I thought I would start with this one as it is one of the least well understood settings. It’s effects are quite subtle, but it can mean the difference between a noisy picture and a clean image, but also between a sharp image and a soft image, in particular in areas of subtle detail or low contrast detail such as foliage, grass and textures.
Crispening is a part of the detail correction circuit. It does not in itself, as it’s name suggests (at least on an EX of F3) make the image “crisper”. What it does is control the contrast range over which the detail circuit operates. Basically it sets the threshold at which detail correction is applied to the image, which in turn can make the image look a little sharper or less sharp. The apparent sharpness itself is controlled by the Detail Level and Frequency controls.
Why is this useful? Well it allows the user to choose whether to opt for a cleaner looking image or a sharper looking image. An important consideration is that this adjustment does not change the actual resolution of the image or the noise level of the camera, but it does make subtle details in the image more or less enhanced and as noise is also a subtle, even if unwanted detail within the image it will also make noise more or less enhanced, thus more or less visible.
In the first illustration I have drawn an imaginary video waveform signal coming from the camera that contains a mixture of noise and both subtle and more obvious picture information. The bigger the up/down change in the waveform the more obvious the change in brightness (and thus contrast) on the monitor or TV would be. Throughout the image there is some noise. I have indicated the noise level for the camera with a pair of red lines. The EX1 and EX3 is a moderately noisy camera, not the worst, nor the best for an HD camera, but pretty good in it’s price range. So if we can do something to make the noise less obvious that would be desirable in many cases. Crispening can help us do that. Crispening ONLY has an effect when you are applying detail correction to the image. It sets the threshold at which detail correction is applied. The default setting on an EX is zero.
If we reduce the crispening setting, lets say to -60, it REDUCES the threshold at which detail is applied which generally makes the pictures look sharper. Looking at the second and third illustrations you can see how if you reduce the threshold too much then detail correction will be applied to even the most subtle changes in the image, including the image noise. The little black spikes I have added to the diagram illustrate the way the detail “enhancement” will be added to both noise and subtle contrast changes as well as larger contrast changes.
This will make the pictures look more noisy, but… and this is important… it will also help bring out subtle low contrast textures in foliage, skin, fabrics etc. A area where perhaps the EX1 and EX3 don’t do terribly well.
If you want a clean image however where noise is less visible, then raising the crispening level to a high positive value, lets say +60 will increase the threshold at which detail correction is added, so signal changes will need to be bigger before detail correction is applied.
With a high positive number the image will look cleaner and less noisy, but you will loose some enhancement in textures and low contrast areas as these will no longer have detail correction applied to them. This can lead to a slightly muddy or textureless look to tress, grass, skin and fabric.
The real problem areas are the subtle textures and low contrast areas (circled in orange) where the true image detail is barely above the noise level. It’s very difficult to bring these out without increasing the appearance of noise. Unfortunately there is no clear answer to how to set the crispening level as it will depend on what you are shooting and how much noise you can tolerate. I tend to have crisping set between +10 and +30 for most things as I do tend to do a fair amount of grading work on my footage. When you grade noise is often the limiting factor as to how far you can push the image, so I like to keep noise under control as much as possible. For green screen and chroma key work I push crispening up to +40 to +60 as this helps me get a cleaner key, especially around subtle edges and hair.
If I am shooting exteriors and scenics with lots of foliage, grass etc then I will sometimes go down to -30 as this helps bring out the subtle textures in the leaves and plants, but this can make noise a little more pronounced, so it’s a trade off. And that’s what Crispening is all about, trading off subtle textures and detail against more visible noise. Ultimately only you can make the choice as to which is more important, but the Crispening level control gives you that choice.
These are the picture profiles that I am currently tending to favour for the EX1, EX1R and EX3. Please remember that picture profiles are entirely subjective. These settings work for me, that doesn’t mean they are perfect or for everyone. I like the images the cameras produce when I use these profiles. Please feel free to adapt them or modify them any way you choose. They work on any of the current EX cameras.
Vivid – Designed to help match the EX to a PDW-700. Gives vivid colours with a small shift away from yellow.
Matrix – Cinema, Matrix Level +60
R-G +8, R-B +10, G-R 0, G-B +15, B-R +5, B-G +6
Detail Level -10 Frequency +20, Crispening -40 (if using gain use crispening +14)
Gamma Cinegamma 1
Black level -3, Black Gamma -35
Low Key Saturation -10
Natural C4 – Designed to give a neutral, natural looking image.
Matrix – Cinema, Matrix Level +35
Detail level -7, Frequency +30, Crispening -40 (if using gain use crispening +20)
Black Level -3, Low key Saturation -15
AC Punch – Gives a very high contrast, bold look.
Matric – Cinema, level +40
Gamma Standard 2, Knee level 80, Slope 0
R-G 0, R-B +1, G-R +12, G-B +2, B-R +11, B-G 0
Detail Level -10, Frequency +30, Crispening -45
Black Level -4, Black Gamma -20.
AC Good to Grade – a general purpose setup to give good grading possibilities.
Matrix – Cinema, Level +25
Gamma Cinegamma 1 (Do not use -3db gain)
Detail Level -7, Frequency +45, Crispening -45 (use +35 if using gain)
Black Level -3.
AC-SD Camera look. To mimic an older SD camcorder based on a DSR400, good for HD to SD conversion.
Matrix – Cinema, Level +15
Detail Level +20, Detail Frequency -35, White Limit +35, Black limit +45
Knee, Manual, Level 90, Slope 0.
Gamma Standard 2, Gamma Level +5
Black Gamma -10
Black Level -10
Enjoy! Any feedback or suggestions welcome. Let me know of any profiles that you come up with that may be of interest to others.
Well I posted here a few days ago about how Data was distributed across the S-Log curve. David williams (thanks David) questioned some of the things in my post raising some valid question over it’s accuracy, so I withdrew the post in order to review it further. While the general principles within the post were correct (to the best of my knowledge and research) and I stand by them, some of the numbers given were not quite right and the data/exposure chart was incorrect.
Before going further lets consider the differences between the a video sensor works and the way our eyes work. A video sensor is a linear device while our own visual system is a logarithmic system. Imagine you are in a room with 8 light fittings, each one with the same power and light output. You start with one lamp on, then turn on another. When you turn on the second lamp the room does not appear to get twice as bright even though the amount of light in the room has actually doubled. Now with two lamps on what happens when you turn on a third? Well you wouldn’t actually notice much of a change. To see a significant change you would need to turn on 2 more lamps. Now with 4 lamps on to see a significant difference you would need to turn on a further 4 lamps. Only adding one or two would make little visual difference. This is because our visual system is essentially a logarithmic system.
Now lets think about F-Stops. An f stop (or T-stop) is a doubling or halving of exposure. So again this is a logarithmic system. If with one light bulb your scene is one stop then to increase the scene brightness by one stop you must double the amount of light, so you would add another light bulb. Now to increase the scene brightness by a further stop you would have to take your existing two light bulbs and double it again to 4 light bulbs, and so on… 2, 4, 8, 16, 32, 64….
Now going back to a video sensor, take a look at the illustrative graph below. The horizontal scale is the number of lightbulbs in our hypothetical room and the vertical scale is the video output from an imaginary video sensor in percent. Please note that I am trying to illustrate a point, the numbers etc are not accurate, I’m just trying to explain something that is perhaps miss-understood by many, simply because it is difficult to understand or poorly explained elsewhere. The important thing to note is that the plotted blue line is a straight line, not a curve because the sensor is a linear device.
Now look at this very similar chart. The only difference now is that I have added an f-stop scale to the horizontal axis. Remember that one f-stop is a doubling of the amount of light, not simply one more lightbulb. I have also changed the vertical scale to data bits. To keep things simple I’m going to use something close 10 bit recording which actually has 956 data bits or steps (bits 64 to 1019 out of 1024 bits), but lets just round that up to 1000 data bits to keep life simple for this example.
So we can see that this imaginary video sensor uses bits 0-50 for the first stop, 50-100 for the second stop, 100-200 for the third stop, 200-400 for the fourth and 400-800 for the fifth. So it is easy to see that huge amounts of data are required to record each stop of over exposure. The brighter the image the more data that is required. Clearly if you want to record a wide dynamic range using a linear system you need massive numbers of data bits for the highlights, while the all important mid tones and shadow areas have relatively little data allocated to them. This is obviously not a desirable situation with current data limited recording systems, you really want to have sufficient data allocated to your mid-tones so that in post production you can grade them satisfactorily.
Now look what happens if we allocate the same amount of data to each stop of exposure. The green line is what you get if, in our imaginary camera we use 200 data bits to record each of our 5 stops of dynamic range. Does the shape of this curve look familiar to anyone? The important note here is that compared to the sensors linear output (the blue line) as the image brightness increases less and less data is being used to record the highlights. This mimics the way we see the world and helps ensure that in the mid ranges where skin tones normally reside there is lots of data to play with in post. Our visual system is most acute in the mid range. that’s because some of the most important things that we see are natural tones, plants, fauna and people. We tend to pay much less attention to highlights as these are rarely of interest to us. Because of this we can afford to reduce the amount of information in video highlights without the end user really noticing. This technique is used by most video cameras when the knee kicks in and compresses highlights. It’s also used by extended gamma curves such as cinegamma’s and hypergamma’s.
Anyone that’s seen a hypergamma curve or cinegamma curve plot will have seen a similar shape of curve. Hypergammas and Cinegammas also use less and less data to record highlights (compared to a linear response) and in many ways achieve a similar improvement in the captured dynamic range.
Hypergammas are not the same as S-Log however. Hypergammas are designed to be useable without grading, even if it’s not ideal. Because of this they stay close to standard gammas in the mid range and it’s only really the highlights that are compressed, this also helps with grading if recording using only an 8 bit codec as the amount of pushing and pulling required to get a natural image is less extreme. However because the Hypergammas allocate more data in the 60 to 90 percent exposure range to stay close to standard gamma the highlights have to be more highly compressed than S-Log so there is less highlight data to work with than with S-Log. If we look at the plot below which now includes an approximate S-Log curve (pink line) you can see that log recording has a much larger difference from a standard gamma in the mid ranges, so heavy grading will be required to get a natural looking image.
Because of the amount of grading that will normally be done with S-Log, recording the output using a 10 bit recorder is all but essential.
When I wrote this article I spent a lot of time studying the Sony S-Log white paper and reading up on S-Log and gamma curves all over the place. One thing that I believe leads to some confusion is the way Sony presents the S-Log data curve in the document. The exposure is plotted against the data bits using stops as opposed to image brightness. This is a little confusing if you are used to seeing traditional plots of gamma curves like the ones I have presented above that plot output against percentage light input. It’s confusing as Sony forget that using stops as the horizontal scale means that the horizontal scale is a log scale and this makes the S-Log ”curve” appear to be a near straight line.
I have not used S-Log on an F3 yet. It will be interesting to see how it compares to Hypergamma in the real world. I’m sure it will bring some advantages as it allows for an 800% exposure range. I welcome any comments or corrections to this article.
I’ve been working some more on picture profiles for the PMW-F3, mainly matrix settings. You can download the full set by clicking here: ac-profiles. Download the zip file, unzip and place the “Sony” folder in the root of an SxS card or SD card in an adapter. Place the card in the camera and go into the “picture profiles” menu and select a picture profile and then “ppdata” and “recall” to load the data into your camera. This will overwrite any PP’s you already have.
Here’s the latest settings I have:
ALL use Detail level -17, Frequency +20, Aperture +25 unless otherwise stated.
AC Warm1: Warm look, less blue/yellow
Cinegamma 1, Black Gamma -25, Black Level -2.
Matrix: Standard, level +8, R-G +14, R-B +12, G-R +4, G-B +8, B-R +4, B-G -18
AC Cool1: Stark cool look, maybe day for night.
Cinegamma 1, Black Gamma -25, Black Level -2.
Matrix: Standard, level +22, R-G -44, R-B -24, G-R -34, G-B =28, B-R -7, B-G -69
AC Elec1: Electronic, vivid look.
Gamma STD1, Black Gamma -20, black level -3, Detail Level -10, Frequency -40
NAT1CG-1: Neutral Look, natural colors, less yellow/green.
Cinegamma 1, Black Level -2
Matrix FL-Light, Level +3, R-G +2, R-B +2, G-R +8, G-B +8, B-R -8, B-G -6
Note that for most of these I have used a cinegamma, that is because I would assume that post work will be done on the footage. If your not planning on doing any grading or post work you should consider using a standard gamma which will give a richer looking image or cinegamma 2 which is broadcast safe.
Why do my pictures go soft when I pan? Camera Detail Correction in depth.
This article is my Christmas present for my readers. When your trying to set up a camera or brew up a picture profile it really helps if you understand the ramifications of each of the settings. I hope this helps explain how detail correction works and how it effects your image.
I am often asked to explain why someones images are going soft when they pan the camera or when there is a lot of movement in the scene. Well this can be down to many things including poor compression or too low a bit rate for the recording, but the two main issues are shutter speed (which is tied in to your frame rate) and detail correction. I’ll cover frame rates and shutter speeds in the near future, but today I’m going to look at Detail Correction.
First of all what is detail correction for? Well originally it was used to compensate for the low resolution of domestic cathode ray tube TV’s and the limited speed at which a CRT TV could go from light to dark. Modern LCD, Plasma and OLED displays handle this much better, but still detail correction remains important to this day to as a way of adding the appearance of additional sharpness to a video image. You’ll often see extreme examples of it on SD TV shows as a dark halo around objects.
The image above is of an imaginary perfect greyscale chart. Looking at it you can see on your screen that each grey bar is quite distinct from the next and the edge between the two is sharp and clear. You computer screen should be quite capable of showing an instant switch from one grey level to the next.
Now if we add the waveform that the “perfect” greyscale would give we can see that the transition from each bar to the next is represented by a nice crisp instant step down, the transition from one bar to the next happening over a single pixel.
The image above represents what a typical video camera might reproduce if it shot the greyscale chart without any form of detail correction or sharpening. Due to the need to avoid aliasing, lens performance and other factors it is impossible to get perfect optical performance so there is some inevitable blurring of the edges between the grey bars. Note that these images are for illustration only, so I have exaggerated the effect. I would expect a good HD camera to still produce a reasonably sharp image.
Looking at the cameras waveform you can see that the nice square edges we saw in on the perfect greyscale waveform have gone and instead the transition from bar to bar is more rounded. Now there are two things that camera manufactures commonly do to correct or compensate for this. One is called aperture correction which is a high frequency signal boost (I’ll explain that another time) but the one were going to look at in this case is called detail correction often simply referred to as “Detail”.
So what happens in the camera? Well the camera constantly compares the video luminance (brightness) levels of the image over a set time period. This time period is incredibly short and in the example given here is the time it takes for the cameras line scan to go left to right from point A to point B. If the difference in the brightness or luminance of the two samples is greater than the threshold set for the application of detail correction (known as crispening on Sony cameras) then the detail circuit kicks in and adds a light or dark enhancement to the brightness change.
With an HD video camera the light or dark edges added by the detail correction circuit are typically only a few pixels wide. On an SD camera they are often much wider. On a Sony camera the detail frequency setting will make the edges thicker (negative value) or thinner (positive value). The Black and White limit settings will limit how bright or how dark the added correction will be and the detail level control determines just how much correction is added to the image overall.
One important thing to consider is that as the amount of detail correction that is applied to the image is dependant on differences in the image luminance measured over time, so you have to consider what happens when the scene is moving or the camera pans. Two things happen when you pan the camera, one is that the image will blur a little due to things moving through the frame while the shutter is open and from line to line objects will be in a slightly different position.
So looking at the waveform we can see that the waveform slope from one grey bar to the next becomes shallower due to the blur induced through the motion of the camera. If we now sample the this slightly blurred image using the same timescale as before we can see that the difference in amplitude (brightness) between the new blue samples at A and B is significantly smaller than the difference between the original red sample points.
What this means in practice is that if the difference between the A and B sample drops below the threshold set for the application of detail correction then it is not applied. So what happens is that as you pan (or there is motion in the scene) the slight image softening due to motion blur will decrease the amount of detail correction being applied to the image so the picture appears to noticeably soften, especially if you are using a high detail correction level.
Detail correction is applied to both horizontal image differences as outlined above and also to vertical differences. As the vertical sampling is taken over 2 or 3 image lines there is much longer time gap between the samples. So when you pan, an object that was in one position on one line may have moved significantly enough by the time the frame scan has progressed 2 more lines that it is in a different position so the detail sampling will be wrong and detail may not be applied at all.
If you are finding that you are seeing an annoying amount of image softening when you pan or move your camera then you may want to consider backing off your detail settings as this will reduce the difference between the detail “on” look and detail “off” look during the pan or movement. If this softens your images too much for your liking then you can compensate by using Aperture Correction (if your camera has this) to boost the sharpness of your image. I’ll explain sharpness in more depth in a later article.
PMW-350 Scene Files for Download
Click on the link above to download a set of my latest scene files. Un-zip and copy to the root of an SxS card, the in the file menu load the files.
These are mainly matrix tweeks. neut2 is one I like that gives rich primary colours while still reasonably true to life. Cine1 is a sudo filmic look Film1 is meant to emulate well saturated film stock DSC-1 is based on Chroma-Du-Monde chart for accurate daylight color Neut is my first matrix tweak for a less green look and warmer skin tones.
There is far too much emphasis on color charts and 100% one to one – set it up with a scope settings. Very often a 100% accurate one to one response won’t look right as the video gamut is smaller and lopsided than that of the human eye so a small amount of skewing of the color gamut can often help produce a picture that visually looks more natural. One of the very best ways to set up a camera is to use a high quality color photograph of a known scene. Shoot the photograph and look at the picture on a monitor and adjust until it looks right. This will give a more natural looking image than aligning with charts and scopes and is a technique that has been used since the very beginnings of color television. I have a scene that contains vibrant colored cars, green fields and trees, buildings and blue sky. I have a dozen large copies of this picture and use it whenever I am making camera adjustments to make sure my pictures still look natural. Of course scopes should still be used if you are making any extreme settings to ensure your images are still legal, but at the end of the day what you are after is an image that looks right too you (or the producer) and whoever else will view your material, not what looks right according to a chart and a scope.
I have been doing a lot of research into the best gammas to use on the EX’s for different lighting situations. The cinegammas are designed for shooting footage that will be graded, the images they produce are not entirely natural looking, however they do maximise dynamic range by compressing highlights and at the same time allocating a large part of the recorded signal range to mid tones and shadow detail. This is why shadows can look washed out or milky. However this also gives you more to play with in the grade.
Cinegamma 1 is tailored for shooting bright scenes or scenes where there will be large areas of highlights. CG1 is tailored for maximum highlight handling with lower shadow dynamic range compared to CG3 and CG4.?Cinegamma 2 is essentially the same as CG1, except the overall level is reduced making it broadcast safe at 0db. Cinegammas 1,3 and 4 all record up to 109% at 0db and 104% at -3db.?Cinegamma 3 has strong highlight compression but the compression starts later than CG1 so it’s not as compressed as CG1. Midtones and shadows are stretched more than CG1. This gives more dynamic range to mid tones and shadows compared to CG1 at the expense of some highlight handling.?Cinegamma 4 is similar to CG3 but with the mid tones lifted still further so that it gives a brighter looking picture overall.
My preference is to use CG1 for outdoor, brightly lit scenes or scenes where highlight handling is critical. Then I use CG3 for indoor and scenes on dull days where extreme highlight handling is less critical, but shadow detail becomes more important. What I have also found is that when shooting interviews the cinegammas work best when they are slightly under exposed compared to standard gammas and then graded in post. If using cinegammas I tend to expose skin tones at around 60%.
Cinegamma 1 on the EX is the same as Hypergamma HG4 on the PDW-700, F900R etc and cineegamma 2 is the same as Hypergamma HG2. With CG1/HG4 : 460% D-range is compressed to 109%.
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