Shadows/Highlights: Difference between revisions

From RawPedia
Jump to navigation Jump to search
(Removed Local Contrast section because the tool was removed, #4247)
No edit summary
 
(4 intermediate revisions by the same user not shown)
Line 1: Line 1:
Use this tool to independently influence the highlights and the shadows of the image.
<div class="pagetitle">Shadows / Highlights</div>


== Sharp Mask ==
== Introduction ==
<gallery caption="Shadows/Highlights "Sharp mask" effect" style="clear: both">
File:Sh_sm_1.jpg|The source image.
File:Sh_sm_2.jpg|"Sharp mask" turned off.
File:Sh_sm_3.jpg|"Sharp mask" turned on.
</gallery>


In order to separate the dark areas from the light ones, a lightness mask (invisible to the user) is created. There are two algorithms for doing this; one blurs the image, while the other retains sharp edges between light and dark zones. Neither one is "better", both have their own merits. The soft mask approach can lead to halos, but it is quick. The sharp mask is slow, but it doesn't cause halos, though it can cause edge artifacts at close inspection.
Use this tool to brighten the shadows or darken the highlights of an image.


== Highlights ==
This tool has received a new engine in RawTherapee 5.5, it now uses an edge-aware [https://arxiv.org/abs/1505.00996 fast guided filter] to prevent halos and operates by default in RGB space to preserve saturation.
The Highlights slider makes the brightest parts of the image less bright without touching the darker tones. To make the effect stronger, use higher values. A slider value of 100 will turn the whites light gray.


== Tonal Width for Highlights ==
== Usage ==
This slider controls the strength of the Highlights slider. Higher values give a stronger effect. A value of 100, combined with Highlights 100, turns the whites into middle gray (you probably won't want that...).


== Shadows ==
Use it in moderation to preserve a natural look. If the photographed scene has a high dynamic range (very deep shadows and very bright highlights) then use the [[Dynamic Range Compression]] tool to compress the dynamic range to a more manageable level, and then optionally use this Shadows/Highlights tool on top of that.
This slider lifts the shadows and applies an effect that is sometimes called 'fill-light' (or 'fill-flash') in other software. Higher values lighten the shadow areas more.


== Tonal Width for Shadows ==
== Interface ==
This slider controls the strength of the Shadows slider. A maximum value of 100 gives the strongest 'lift shadows' effect.


== Radius ==
=== Color Space ===
The value of the Radius slider influences the Highlights, Shadows and Local Contrast sliders. The larger the radius, the stronger the effect of local contrast. The effective area of the Highlights and Shadows sliders also increases.


If you are bored, set the first four sliders to 100 and play with Local Contrast to transform your favorite raw processor into a cheap effect machine!
Adjusting shadows and highlights in the RGB space preserves image saturation which usually looks more natural than working in L*a*b* space which tends to desaturate affected areas. However, in some cases working in RGB space may oversaturate the shadows, in which case you should switch to L*a*b* space.
 
=== Shadows ===
 
Allows you to brighten the darkest parts of the image
 
=== Highlights ===
 
Allows you to darken the brightest parts of the image.
 
=== Tonal Width ===
 
Shadows/Highlights Tonal Width allows you to control how bright an area must be for it to be affected by the highlights slider, and how dark an area must be for it to be affected by the shadows slider. Though the underlying math is a bit more complicated, think of a histogram - the highlights tonal width specifies the range of tones from the white end of the histogram which the highlights slider will affect, and the shadows tonal width specifies the range of tones from the black end of the histogram which the shadows slider will affect. The higher the tonal width value, the more tones are affected.
 
=== Radius ===
 
The value of the Radius slider influences the effective area of the Shadows and Highlights sliders.

Latest revision as of 21:40, 9 December 2019

Shadows / Highlights

Introduction

Use this tool to brighten the shadows or darken the highlights of an image.

This tool has received a new engine in RawTherapee 5.5, it now uses an edge-aware fast guided filter to prevent halos and operates by default in RGB space to preserve saturation.

Usage

Use it in moderation to preserve a natural look. If the photographed scene has a high dynamic range (very deep shadows and very bright highlights) then use the Dynamic Range Compression tool to compress the dynamic range to a more manageable level, and then optionally use this Shadows/Highlights tool on top of that.

Interface

Color Space

Adjusting shadows and highlights in the RGB space preserves image saturation which usually looks more natural than working in L*a*b* space which tends to desaturate affected areas. However, in some cases working in RGB space may oversaturate the shadows, in which case you should switch to L*a*b* space.

Shadows

Allows you to brighten the darkest parts of the image

Highlights

Allows you to darken the brightest parts of the image.

Tonal Width

Shadows/Highlights Tonal Width allows you to control how bright an area must be for it to be affected by the highlights slider, and how dark an area must be for it to be affected by the shadows slider. Though the underlying math is a bit more complicated, think of a histogram - the highlights tonal width specifies the range of tones from the white end of the histogram which the highlights slider will affect, and the shadows tonal width specifies the range of tones from the black end of the histogram which the shadows slider will affect. The higher the tonal width value, the more tones are affected.

Radius

The value of the Radius slider influences the effective area of the Shadows and Highlights sliders.