Multi-Camera Matching and Creating a Streaming Picture Profile Using the Sony PMW-300K1

Our primary focus in this article is to lay down a process to help you match your cameras for multi-camera live streaming production. 如果你曾经制作过多镜头拍摄, 你可能注意到了黑人的变化, 白人, 相机之间的颜色. 这些变化可以巧妙地将观众带离“当下”,” stopping them from fully immersing in the event and/or story you are producing.

There have been times in shows when we have “matched” cameras to our eyes, and everything seemed to be the same and then someone with a bright magenta shirt would walk on stage and that color magenta would be different on all the camera angles. 这显然给观众留下了错误的印象. 通过使用矢量镜和波形和下面的过程, you can limit these variables and ensure your audience has an immersive experience, 至少在视频质量方面是这样.

您几乎可以将所有这些过程应用于任何摄像机, 但是为了具体起见, 我们将在索尼PMW-300K1上演示此过程, a camera that we use frequently and one that’s well-suited to streaming production.

索尼PMW-300K1是古老的PMW-EX3的升级版, a game-changing video camera for low to medium-sized budget productions. 2008年发行, EX3的价格点, 形成的因素, 镜头的互换性, 其他特性, 迅速跃升为行业主力.

随着2013年10月PMW-300的发布, 索尼增加了更好的信号处理, MPEG HD422 50Mbps recording (plus XAVC-Intra 100Mbps and XAVC Long 50/35/25Mbps recording in 10-bit), and a new Multi-Matrix mode to picture profiles among other enhancements. The new Multi-Matrix mode allows for even finer tuning of color than the EX3.

理解波形和矢量镜

匹配摄像机时, the two most important diagnostic tools available to the operator are waveform and vectorscope. A waveform monitor displays the luminance (brightness) values within an image, 而矢量镜显示色度(颜色)值.

波形

图1(下面) 显示Leader LV5330测试监视器的波形监视器, displaying luminance values for the 3 color channels within the image (RGB). This method of displaying color channels separately is referred to as Parade mode, 并且是精确配色所必需的. 如左上角的“RGB”所示, 显示器显示红色, 绿色, 蓝色从左到右. 注意字母出现的顺序是很重要的, 因为有些显示器会显示红色, 蓝色的, 从左到右为绿色, 在这种情况下，符号将读取“RBG”.亮度级别显示在y轴上, 表示IRE值，取值范围为0 ~ 110, 0代表绝对黑色, 110代表纯白色过度曝光.

图1. The Leader LV5330 test monitor’s waveform monitor displays luminance values for the 3 color channels in traditional red-green-blue (RGB) order.

在图1中, the lines on the waveform are all relatively straight because the image being analyzed is of a 白色 card that is evenly lit. The waveform represents the exposure values across the image from left to right. That is because the waveform is being displayed horizontally (referred to as a horizontal sweep). 波形 monitors generally allow for waveform viewing vertically (i.e.(垂直扫)，从上到下. Both vertical and horizontal viewing are necessary for proper lens shading.

矢量显示器

图2(下面) shows the LV5330’s vectorscope displaying chrominance values for the incoming feeds. A vectorscope has six points of color reference around the inside edge of the circle, 每个都用一个盒子来表示，盒子里有一组准星.

图2. The LV5330’s vectorscope displays chrominance values for incoming feeds.

从尽可能靠近中心的圆的顶部开始, 从这里开始顺时针移动, 颜色是红色(R), 红色(M), 蓝色(B), 青色(C), 绿色(G), 黄色(Y). These points represent color standards that have been set across the film and broadcast industries.

使用矢量镜时，必须附有准确的芯片图(下面的图3), which displays colors to represent each of the above-mentioned color points on the scope. 取决于所使用的图表类型, 显示的彩色芯片数量可能会有所不同, but all accurate charts will at the very least display the 6 vector colors. 大多数图表还将显示11阶交叉灰度, showing 9 values of gray between 白色 and black in both directions.

图3. DSC实验室芯片图.

更高级的图表显示大范围的颜色值, 这样你就可以在匹配相机时进行更精细的调整. These additional colors will generally include 4 different representations of common human skin tones (下面的图4). These skin tone swatches can be extremely helpful when matching PMW300K1s, as ensuring consistency in skin tones between cameras is of utmost importance. Skin tone points will fall on the line between Yellow and Red on the scope.

图4. 矢量镜肤色.

矢量镜的中心表示缺少颜色(黑色), 白色, 以及图像中包含的所有灰度值). 随着颜色的引入, the points on the scope move out from the center towards the colors that are being displayed. 一个点离中心越远, the higher the saturation (aka chrominance) for that given color value. 校准相机时, the goal is to have each of the color points fall exactly in the center of their respective boxes.