In the last few years, MTF has become a buzzword in both cine and HD lens circles, but there is still a lot of confusion about just what it is, what it can and can’t do, and what it means to the cinematographer in a practical sense. In this article, I will attempt to clear up some this confusion by explaining what MTF means from a technical standpoint.

You may already know that MTF is an abbreviation for Modulation Transfer Function. MTF provides a way to objectively measure image sharpness in a practical and repeatable way that also correlates well with subjective perceived image sharpness.

The smallest practical unit for measuring image detail is a line pair, which is a black line and a white line, side by side. The measurement is line pairs per millimeter, and not lines per millimeter. It is very important to note that we are always talking about a black and a white line pair, and we are counting them as one line pair (1 lp/mm). In the digital realm, we need at least one pixel to represent the black point, and one to represent the white point. So we need a minimum of 2 pixels to image 1 line pair.

…continue reading What Is MTF?

This has been out for a while, but it doesn’t seem to have been widely circulated. Sony has a white paper on S-Log which describes the intended use of S-Log gamma, from production to post. Of particular interest to compositors and colorists are the formulas for translating between S-Log and Linear Light.

Download the S-Log White Paper here.

I guess you could call this “HD Formats for Dummies”, but if you’ve been reading our blog, you are certainly no dummy. There are so many varieties of HD out there and it can all get a little confusing. My aim here is to help organize the different formats and clear up some common misconceptions. To do this I’ve broken down the HD formats into three categories: Resolution, Frequency, and Frame Rate. With these three parameters, you can come up with any HD signal available. Keep in mind that not all the HD formats we will discuss can be sent for broadcast, so I will also point out those formats and how they effect your final product.

…continue reading Making Sense of HD Formats and Frame Rates

In the vast shadow of the release of James Cameron’s Avatar, the Blu-ray Disc Association released the finalized 3D specifications. 3D media has bounced in and out of pop culture since the 1950s when it was introduced as a way for motion pictures to compete with television. Now the home entertainment industry has embraced 3D technology with a method for delivering the media.

Blu-ray 3D will be 1080p and backward compatible, meaning that the disks will be playable and viewable as 2D on existing equipment and current disks will play on any new equipment. The new compression codec is known as MPC, a variant of the current AVC. Importantly, the new standard will work with “any compatible 3D display,” which sounds vague, but appears to mean that there won’t be any format wars between different monitoring technologies. There are active and passive displays with high and low refresh rates, and side-by-side and line-interweaved technologies. Get ready for a whole new set of specs as different flat screen monitors debut for the home and the professional industry. 3D will work this time because the display technology will drive it directly to the audience. Even the Sony PlayStation 3 is included in the new Blu-ray 3D spec. Soon 3D will be yet another creative tool available to the creative cinematographer – instead of asking for a focus pull or a small dolly creep, perhaps that next dramatic moment will be best punctuated with a “depth pull.”

…continue reading Blu-ray 3D Standard Announced

Over Thanksgiving weekend, there was a discussion on the Cinematographer’s Mailing List (CML, cinematography.net) about new camera technologies and future trends in our industry. Neil Smith of Hollywood DI asked me to give Abel’s perspective on what’s to come. Since writing my response, numerous people have commented on it and suggested we re-post it for others to see. It is presented here for you to read and draw your own conclusions.

From Neil Smith, Hollywood DI:

Mitch, I’d be interested to hear your views on how you see the industry changing over the next 12 months … you guys have been in the game a lot longer than most of us and have never ceased to adapt and change and continue to deliver great products and services.

My response:

What we see as the big change in the industry is how the market now leads the manufacturers. Unlike what so many sometimes think, the manufacturers have always tried to listen to their customers to develop products with which everyone will be happy. Focus groups and meetings with large clients worked well in the past, but the business of Image Capture has expanded at an exponential rate. And there are also forums such as this that communicate in minutes what once took months. There are different markets and different ways to serve them. And these markets are letting the manufacturers know this, and the manufacturers are responding. And sometimes a manufacturer just might know something and drop a product that makes everyone stop and take notice.

…continue reading So, What Lies Ahead?

This is the first part of the ENG Essentials – Camera Matching series, and the first step to matching two cameras. White Shading is an in-camera process where a lens is matched with a camera’s sensor. Every lens and every sensor have unique characteristics, and the combination will often produce uneven color across your image. White shading corrects for this uneven color by adjusting individual color channels (R,G,B) from top and bottom and from left to right. This is done with a Leader waveform monitor and a white sphere that is designed to produce even white light.

Another important step after white shading a camera is to match white balance values. All pro cameras have preset and user defined white balance values – the P,A,B switch. If you run a white balance on two cameras looking at the same white card, in the same lighting environment, you will get very similar results. But if you plan to use the preset values (3200K,5600K) we need to be sure that both camera actually produce the same color white. Different lenses produce different white values, so even though the camera thinks you are at 3200K, it may be completely wrong. This can be corrected for by adjusting offset values in the camera, and making sure that both cameras have matching white values.

Watch my video below to see how these two steps are done.

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(Photo credit: Evin Grant)

Did you ever wonder what creates permanently lit, or what we often refer to as “blown”, pixels in your CCD camera’s imager? Here’s the reason:

Charged-Coupled Devices (CCD’s) are made up of an array of millions of photodiodes, which turn light into voltage. Photodiodes have two leads coming from the bottom, a cathode and an anode. When a photon of energy strikes the diode, it excites an electron, creating a mobile electron and a positively charged electron hole. Holes move toward the anode, and electrons toward the cathode, producing a photocurrent. Because photodiodes use voltage to convey information, they can be susceptible to high-energy particles such as cosmic rays.

…continue reading Lit Pixels: Why Do They Happen?