Credit Andrea - minor clarifications for plugins which do clipping in the case of HDR

diff --git a/parts/Plugins.tex b/parts/Plugins.tex
index a04852c99c84d27ab3dcc491f75cf6f8f17edd86..8661d2667a60690154c87e78745d9e3c62a7c71f 100644 (file)
--- a/parts/Plugins.tex
+++ b/parts/Plugins.tex
@@ -1543,7 +1543,7 @@ If you are building an alpha selection mask by first intersection and then union
 \label{sub:blur}
 \index{blur}
 
-This is a Gaussian type blur. Other blur plugins -- \textit{Linear}, \textit{Motion}, \textit{Radial}, and \textit{Zoom} --are described later. This plugin is keyframable. Blur is used to blur a video track via the following parameters:
+This is a Gaussian type blur. Other blur plugins -- \textit{Linear}, \textit{Motion}, \textit{Radial}, and \textit{Zoom} --are described later. This plugin is keyframable. In case the frame is HDR, this plugin introduces a clip to prevent pixel values outside the normalized range (0, 1.0f). Blur is used to blur a video track via the following parameters:
 \begin{description}
     \item[Horizontal and vertical] values are used to tell which one of the fields blurring affects; can be both.
     \item[Radius] use this dial to define the amount of blur to apply.
@@ -1888,7 +1888,7 @@ Since \textit{complementary colors} are neutralized, to eliminate a \textit{colo
 This plugin is a tool that can be used to convert your input media, such as a recording from your camera,
 from one color space/range to another.  It works for both RGB and YUV as set by your project format.
 Options are BT601, BT709, or BT2020 for Color Space input and output and JPEG or MPEG for Color Range
-input and output.  The Inverse option checkbox is available in case your media was rendered in the wrong
+input and output. In case the frame is HDR, this plugin introduces a clip to prevent pixel values outside the normalized range (0, 1.0f). The Inverse option checkbox is available in case your media was rendered in the wrong
 color space  or range so that you can fix it.
 
 \begin{figure}[H]
@@ -2158,7 +2158,7 @@ This effect flips a video track either vertically or horizontally.
 \index{foreground}
 
 Whatever the visual content of the frame, the Foreground plugin application applies a uniform color that can be chosen by color picker, color wheel, color presets, or by entering the hexadecimal value.
-In addition there are HSV, RGB, YUV, and alpha sliders to vary the color accordingly.
+In addition there are HSV, RGB, YUV, and alpha sliders to vary the color accordingly. In case the frame is HDR, this plugin introduces a clip to prevent pixel values outside the normalized range (0, 1.0f).
 
 \subsection{Frames to fields}%
 \label{sub:frames_to_fields}
@@ -2335,14 +2335,8 @@ The histogram allows an immediate view of the contrast amplitude of an image wit
     \label{fig:histogram}
 \end{figure}
 
-The Histogram is always performed in floating point RGB regardless of
-the project color space, but with clipping at 1.0. When using the X11
-graphics driver and RGBA-FLOAT color model, Histogram allows you to
-display greater than (0 - 1.0f) values to accomodate HDR. This does
-not work when using X11-OpenGL because it is an 8-bit limited driver.
-The display will stop at +110\%, but there is no clipping. By lowering
-the brightness all out-of-range values become visible, even those
-initially above 110\%.
+The Histogram is always performed in floating point RGB regardless of the project color space, but with clipping at 1.0. When using the X11 graphics driver and RGBA-FLOAT color model, Histogram allows you to read pixels value greater than (0 - 1.0f), But these values are not displayed in the Compositor window. to accomodate HDR. This does not work when using X11-OpenGL because it is an 8-bit limited driver. The display will stop at +110\%, but there is no clipping. By lowering
+the brightness all out-of-range values become visible (tone mapping), even those initially above 110\%.
 
 The histogram has two sets of transfer parameters: the \textit{input transfer} and the \textit{output transfer}. The input transfer has value on the horizontal axis of $x$; it is a normalized scale of values ranging from 0 - 1.0 (which for a depth color of 8 bits corresponds to the range 0 - 255, for 10 bits corresponds to 0 - 65536, etc). The output transfer (the $y axis$) represents the height of the column where a given value $x$ appears. A higher column ($y$ greater) indicates that many pixels have the corresponding value $x$; a lower column indicates that fewer pixels have that value. On the left we have the minimum value $0$, which is the black point. On the right we have the maximum value $1.0$ which is the white point. The intermediate values pass smoothly from one extreme to the other. The three important points (including the midtones) are indicated by cursors (small triangles) at the base of the histogram. You can adjust them to change the values of the three points if you want. Acting on the white or black point involves horizontal shifts only; acting on the midtones triangle also involves vertical movements leading to a "gamma" correction of the curve (Linear to Log or Reverse Log or vice versa). Further down is an additional bar with related cursors and textboxes. It is used to adjust input and output values (on the vertical).
 
@@ -2447,7 +2441,7 @@ So, by reporting the sum the shape of the results are more similar to Bezier.
 \label{sub:histogram_bezier_curves}
 \index{histogram Bezier}
 
-Histogram Bézier allows an immediate view of the contrast amplitude of an image with its distribution of luma and colors values using a piecewise linear method (bins). In addition it uses a Bézier curve (parametric) on the histogram plot. When mapping color spaces, it has a variety of presentations to get smoother transitions and more pleasing output. It uses more general remapping, not just straight lines but more contour lines. Curves are perhaps the most powerful and sophisticated tool for color correction. For some repetitive details, see the previous description of the Histogram plugin. Histogram Bézier is keyframable. The scale is given in percent ($0 - 100\% \pm 10\%$). The default curve is Log type and can use either RGB or YUV sources without implementing conversions.
+Histogram Bézier allows an immediate view of the contrast amplitude of an image with its distribution of luma and colors values using a piecewise linear method (bins). In addition it uses a Bézier curve (parametric) on the histogram plot. When mapping color spaces, it has a variety of presentations to get smoother transitions and more pleasing output. It uses more general remapping, not just straight lines but more contour lines. Curves are perhaps the most powerful and sophisticated tool for color correction. For some repetitive details, see the previous description of the Histogram plugin. Histogram Bézier is keyframable. The scale is given in percent ($0 - 100\% \pm 10\%$). In case the frame is HDR, this plugin introduces a clip to prevent pixel values outside the normalized range (0, 1.0). The default curve is Log type and can use either RGB or YUV sources without implementing conversions.
 
 NOTE: Histogram Bezier may give results that are not congruent with Histogram plugin. To understand the difference in behavior see the Theory section in Histogram plugin.