\subsubsection{Image Sequences}
\label{ssub:ffmpeg_image_sequences}
-The image sequences can be uncompressed, with lossy or lossless compression but always Intraframe. They are suitable for post-processing that is compositing (VFX) and color correction.
+The image sequences can be uncompressed, with lossy or lossless compression but always Intraframe. They are suitable for post-processing that is compositing (VFX) and color correction. Note: even if \CGG{} outputs fp32, exr/tiff values there are normalized to 0-1.0f.
\begin{description}
\item[DPX] Film standard; uncompressed; high quality. \textit{Log} type.
\subsubsection{Image Sequences}
\label{sub:internal_image_sequences}
-There are quite a few formats available.
+There are quite a few formats available. Note: even if \CGG{} outputs fp32, exr/tiff values there are normalized to 0-1.0f.
\begin{description}
\item[EXR Sequence] OpenEXR (Open Standard) is a competing film standard to DPX, but \textit{Linear} type.
\begin{description}
\item[Color primaries]: the gamut of the color space associated with the media, sensor, or device (display, for example).
\item[Transfer characteristic function]: converts linear values to non-linear values (e.g. logarithmic). It is also called Gamma correction.
- \item[Color matrix function] (scaler): converts from one color model to another. $RGB \leftrightarrow YUV$; $RGB \leftrightarrow YCbCr$; etc.
+ \item[Color matrix function] (scaler): converts from one color model to another. $RGB \leftrightarrow YUV$; $RGB \leftrightarrow Y'CbCr$; etc.
\end{description}
The camera sensors are always RGB and linear. Generally, those values get converted to YUV in the files that are produced, because it is a more efficient format thanks to chroma subsampling, and produces smaller files (even if of lower quality, i.e. you lose part of the colors data). The conversion is nonlinear and so it concerns the "transfer characteristic" or gamma. The encoder gets input YUV and compresses that. It stores the transfer function as metadata if provided.
Not having \CGG{} a CMS, it becomes essential to have a monitor calibrated and set in sRGB that is just the output displayed on the timeline of the program. You have these cases:
\begin{center}
- \begin{tabular}{ |l|l|l| }
+ \begin{tabular}{|l|l|p{8cm}|}
\hline
\textbf{Timeline} & \textbf{Display} & \textbf{Description} \\
\hline
Let us give an example of color workflow in \CGG{}. We start with a source of type YUV (probably: YCbCr); this is decoded and converted to the chosen color model for the project, resulting in a \textit{temporary}. Various jobs and conversions are done in FLOAT math and the result remains in the chosen color model until further action. In addition, the temporary is always converted to sRGB 8-bit for monitor display only. If we apply the \texttt{ChromaKey (HSV)} plugin, the temporary is converted to HSV (in FLOAT math) and the result in the temporary becomes HSV. If we do other jobs the temporary is again converted to the set color model (or others if there is demand) to perform the other actions. At the end of all jobs, the obtained temporary will be the basis of the rendering that will be implemented according to the choice of codecs in the render window (\textit{Wrench}), regardless of the color model set in the project. If we have worked well the final temporary will retain as much of the source color data as possible and will be a good basis for encoding of whatever type it is.
For practical guidelines, one can imagine starting with a quality file, for example, \textit{10-bit YUV 4.2.2}. You set the project to \texttt{RGBA-FLOAT}; the \texttt{YUV color space} to your choice of Rec709 (for a FullHD) or BT 2020NCL (for UHD) and finally the \texttt{YUV color range} to JPEG. If the original file has the MPEG type color range then you convert to JPEG with the \texttt{ColorSpace} plugin. If you want to transcode to a quality intermediate you can use \textit{DNxHR 422}, or even \textit{444}, and maybe do the editing step with a \textit{proxy}. For rendering you choose the codec appropriate for the file destination, but you can still generate a high-quality master, for example \textit{ffv1 .mov} with lossless compression.
+
+\begin{figure}[htpb]
+ \centering
+ \includegraphics[width=1.0\linewidth]{color_01.png}
+ \caption{Color settings (Settings $\rightarrow$ Format / Settings $\rightarrow$ Preferences)}
+ \label{fig:color_01}
+\end{figure}
projects / goodguy / cin-manual-latex.git / blobdiff