Tone Mapping - Revision history

DrSlony at 21:40, 9 December 2019

2019-12-09T21:40:47Z

← Older revision		Revision as of 21:40, 9 December 2019
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			<div class="pagetitle">Tone Mapping</div>

	The effects of this tool are visible at any zoom level. However, due to the nature of the algorithm, only the 1:1 (or more) preview zoom will match the saved image perfectly. If you are zoomed out at less than 1:1, you should be aware that the preview can match the saved image very well or not so well, depending on the "''Edge Stopping''" and "''Scale''" sliders. Read the "[[Tone Mapping#Getting the preview to match the saved image \| Getting the preview to match the saved image]]" section below. Use a detail window (click on the [[File:Window-add.png]] icon under the [[The_Image_Editor_Tab#The_Preview_Panel \| main preview panel]]) to inspect a part of the image, or zoom the main preview to 100% (also called 1:1) [[File:Magnifier-1to1.png]].		The effects of this tool are visible at any zoom level. However, due to the nature of the algorithm, only the 1:1 (or more) preview zoom will match the saved image perfectly. If you are zoomed out at less than 1:1, you should be aware that the preview can match the saved image very well or not so well, depending on the "''Edge Stopping''" and "''Scale''" sliders. Read the "[[Tone Mapping#Getting the preview to match the saved image \| Getting the preview to match the saved image]]" section below. Use a detail window (click on the [[File:Window-add.png]] icon under the [[The_Image_Editor_Tab#The_Preview_Panel \| main preview panel]]) to inspect a part of the image, or zoom the main preview to 100% (also called 1:1) [[File:Magnifier-1to1.png]].

DrSlony: updated icons

2018-11-22T21:28:09Z

updated icons

← Older revision		Revision as of 21:28, 22 November 2018
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	The effects of this tool are visible at any zoom level. However, due to the nature of the algorithm, only the 1:1 (or more) preview zoom will match the saved image perfectly. If you are zoomed out at less than 1:1, you should be aware that the preview can match the saved image very well or not so well, depending on the "''Edge Stopping''" and "''Scale''" sliders. Read the "[[Tone Mapping#Getting the preview to match the saved image \| Getting the preview to match the saved image]]" section below. Use a detail window (click on the [[~~image~~:~~New~~-~~detail-window~~.png]] icon under the [[The_Image_Editor_Tab#The_Preview_Panel \| main preview panel]]) to inspect a part of the image, or zoom the main preview to 100% (also called 1:1) [[~~image~~:~~Gtk-zoom~~-~~100~~.png]].		The effects of this tool are visible at any zoom level. However, due to the nature of the algorithm, only the 1:1 (or more) preview zoom will match the saved image perfectly. If you are zoomed out at less than 1:1, you should be aware that the preview can match the saved image very well or not so well, depending on the "''Edge Stopping''" and "''Scale''" sliders. Read the "[[Tone Mapping#Getting the preview to match the saved image \| Getting the preview to match the saved image]]" section below. Use a detail window (click on the [[File:Window-add.png]] icon under the [[The_Image_Editor_Tab#The_Preview_Panel \| main preview panel]]) to inspect a part of the image, or zoom the main preview to 100% (also called 1:1) [[File:Magnifier-1to1.png]].

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DrSlony at 21:47, 13 January 2018

2018-01-13T21:47:36Z

← Older revision		Revision as of 21:47, 13 January 2018
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	[[Image:Rt407-ba-tonemapping-hdr-cropped.jpg\|thumb\|Tone mapping was used on this high dynamic range (HDR) 32-bit TIFF image to make it look aesthetically pleasing and viewable on low dynamic range media, such as a computer screen or on paper.]]		[[Image:Rt407-ba-tonemapping-hdr-cropped.jpg\|thumb\|Tone mapping was used on this high dynamic range (HDR) 32-bit TIFF image to make it look aesthetically pleasing and viewable on low dynamic range media, such as a computer screen or on paper.]]
	The Tone Mapping tool can be used to lift the dark areas of your photo in a way that prevents halos from appearing, and it can be used to bring out or suppress detail, to make the photo more crisp or more 'dreamy'. Tone mapping adjusts the global contrast of an image differently from the local contrast. Specifically, it's very useful for decreasing large scale contrasts while preserving (or boosting) small scale contrasts. The method used is taken from ''Edge-Preserving Decompositions for Tone and Detail Manipulation'' with some modifications.		The Tone Mapping tool can be used to lift the dark areas of your photo in a way that prevents halos from appearing, and it can be used to bring out or suppress detail, to make the photo more crisp or more 'dreamy'. Tone mapping adjusts the global contrast of an image differently from the local contrast. Specifically, it's very useful for decreasing large scale contrasts while preserving (or boosting) small scale contrasts. The method used is taken from ''Edge-Preserving Decompositions for Multi-Scale Tone and Detail Manipulation'' with some modifications.

	Note: tone mapping requires a lot of memory (RAM) and is CPU-intensive.		Note: tone mapping requires a lot of memory (RAM) and is CPU-intensive.

DrSlony: /* Getting the preview to match the saved image */

2017-03-27T19:06:33Z

Getting the preview to match the saved image

← Older revision		Revision as of 19:06, 27 March 2017
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	The effects of this tool highly depend on the size of the input image in the engine's toolchain. To keep the preview fast, RawTherapee feeds each tool with the image you see in the preview at the same resolution as the preview, not the original, huge one (however, when you save an image, it uses the original, huge one, which is why saving takes longer). Processing a 900x600 image is much faster than processing a 7360x4912 one, for instance. The side-effects of this are that the zoomed-out preview may not match the saved image, depending on the "''Edge Stopping''" and "''Scale''" sliders.		The effects of this tool highly depend on the size of the input image in the engine's toolchain. To keep the preview fast, RawTherapee feeds each tool with the image you see in the preview at the same resolution as the preview, not the original, huge one (however, when you save an image, it uses the original, huge one, which is why saving takes longer). Processing a 900x600 image is much faster than processing a 7360x4912 one, for instance. The side-effects of this are that the zoomed-out preview may not match the saved image, depending on the "''Edge Stopping''" and "''Scale''" sliders.

	~~You will find that the~~ default values for this tool are Edge Stopping=1.40 and Scale=1.00. These values generally lead to ~~great~~ results~~, but specifically the Scale value is the one~~ which ~~leads to differences between~~ the ~~zoomed-out preview and~~ saved image. If you ~~set Scale=0.10 (~~the ~~minimum) while tweaking your zoomed-out photo in RawTherapee, and then, just before saving it,~~ you change it to ~~Scale=1.00,~~ the saved image ~~will match~~ the ~~zoomed-out preview very well. Use this trick to get~~ the ~~preview~~ to ~~match~~ the ~~saved~~ image. ~~It works best when Edge Stopping is around 1.40.~~ Remember that if you zoom the preview to 100%, it will perfectly match the saved image regardless of what slider values you use.		The default values for this tool are Edge Stopping=0.5 and Scale=0.10. These values generally lead to good results and a preview which quite closely matches the saved image. If you wish to adjust these values, you will need to process the full image every time you change them to make sure that their effects on the saved output are what you had in mind. An easy way to simplify this task is by setting an image viewer as the "[[Preferences#External_Editor\|External editor]]", then you just hit the keyboard shortcut Ctrl+e to have RawTherapee fully process the image and automatically view it in your image viewer.

			Remember that if you zoom the preview to 100%, it will perfectly match the saved image regardless of what slider values you use.
	<br style="clear: both" />		<br style="clear: both" />

	==Interface Description ==		==Interface Description ==
	=== Strength ===		=== Strength ===

DrSlony: Updated

2015-04-18T14:04:42Z

Updated

New page

The effects of this tool are visible at any zoom level. However, due to the nature of the algorithm, only the 1:1 (or more) preview zoom will match the saved image perfectly. If you are zoomed out at less than 1:1, you should be aware that the preview can match the saved image very well or not so well, depending on the "''Edge Stopping''" and "''Scale''" sliders. Read the "[[Tone Mapping#Getting the preview to match the saved image | Getting the preview to match the saved image]]" section below. Use a detail window (click on the [[image:New-detail-window.png]] icon under the [[The_Image_Editor_Tab#The_Preview_Panel | main preview panel]]) to inspect a part of the image, or zoom the main preview to 100% (also called 1:1) [[image:Gtk-zoom-100.png]].

----

[[Image:Rt407-ba-tonemapping-hdr-cropped.jpg|thumb|Tone mapping was used on this high dynamic range (HDR) 32-bit TIFF image to make it look aesthetically pleasing and viewable on low dynamic range media, such as a computer screen or on paper.]]
The Tone Mapping tool can be used to lift the dark areas of your photo in a way that prevents halos from appearing, and it can be used to bring out or suppress detail, to make the photo more crisp or more 'dreamy'. Tone mapping adjusts the global contrast of an image differently from the local contrast. Specifically, it's very useful for decreasing large scale contrasts while preserving (or boosting) small scale contrasts. The method used is taken from ''Edge-Preserving Decompositions for Tone and Detail Manipulation'' with some modifications.

Note: tone mapping requires a lot of memory (RAM) and is CPU-intensive.

== Getting the preview to match the saved image ==
<gallery style="float: right" caption="Getting the Tone Mapping preview to match the saved image" perrow="2">
Image:Rt tm preview.jpg|Edge Stopping=1.40 and Scale=0.10 while editing, but Scale is set to 1.00 just before saving.
Image:Rt tm saved.jpg|Using this trick, the preview matches the saved image very well.
</gallery>
The effects of this tool highly depend on the size of the input image in the engine's toolchain. To keep the preview fast, RawTherapee feeds each tool with the image you see in the preview at the same resolution as the preview, not the original, huge one (however, when you save an image, it uses the original, huge one, which is why saving takes longer). Processing a 900x600 image is much faster than processing a 7360x4912 one, for instance. The side-effects of this are that the zoomed-out preview may not match the saved image, depending on the "''Edge Stopping''" and "''Scale''" sliders.

You will find that the default values for this tool are Edge Stopping=1.40 and Scale=1.00. These values generally lead to great results, but specifically the Scale value is the one which leads to differences between the zoomed-out preview and saved image. If you set Scale=0.10 (the minimum) while tweaking your zoomed-out photo in RawTherapee, and then, just before saving it, you change it to Scale=1.00, the saved image will match the zoomed-out preview very well. Use this trick to get the preview to match the saved image. It works best when Edge Stopping is around 1.40. Remember that if you zoom the preview to 100%, it will perfectly match the saved image regardless of what slider values you use.
<br style="clear: both" />
==Interface Description ==
=== Strength ===
This controls the strength of the overall effect. As of version 4.2.156, as you increase the strength, shadows are raised and highlights are slightly lowered in a way which aims to preserve the average luminance of the image thereby preventing the washed-out look.

=== Gamma ===
Gamma moves the action of tone-mapping to shadows or highlights.

=== Edge Stopping ===
This parameter affects sensitivity to edges. The greater it is the more likely an illumination change is to be considered an "edge". If set to zero tone mapping will have an effect similar to [https://en.wikipedia.org/wiki/Unsharp_masking unsharp masking].

=== Scale ===
This control gives meaning to the difference between "local" and "global" contrast; the greater it is the larger a detail needs to be in order to be boosted. See the note above on the influence this setting has on the preview vs the saved image.

=== Reweighting Iterates ===
In some cases tone mapping may result in a cartoonish appearance, and in some rare cases soft but wide halos may appear. Increasing the number of reweighting iterates will help fight some of these problems. When more than zero reweighting iterates are used, the best results will be had if the edge stopping parameter is set to one (technical detail: this results in a 1-norm approximation of the smoothness using iteratively reweighted least squares). Artifacts in high contrast edges may begin to appear when this value is set to about 1.8 or higher.