Local Lab Controls - Revision history

DrSlony: DrSlony moved page Local Lab controls/ to Local Lab Controls without leaving a redirect

2018-07-18T08:46:27Z

DrSlony moved page Local Lab controls/ to Local Lab Controls without leaving a redirect

← Older revision	Revision as of 08:46, 18 July 2018
(No difference)

DrSlony: Removed British-English spelling

2018-07-18T08:44:59Z

Removed British-English spelling

Sguyader: /* Processing time and memory use */

2017-11-20T00:11:26Z

Processing time and memory use

← Older revision		Revision as of 00:11, 20 November 2017
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	Two settings have a strong influence on resource use:		Two settings have a strong influence on resource use:
	• “Denoise” which adds around 1 sec. of processing time, and 1 MB of memory use;		* “Denoise” which adds around 1 sec. of processing time, and 1 MB of memory use;
	• “Global quality: Enhanced + chroma denoise” which adds around 0.5 sec. And 0.6 MB.		* “Global quality: Enhanced + chroma denoise” which adds around 0.5 sec. And 0.6 MB.
	These figures depend on the size of the RT-spot.		These figures depend on the size of the RT-spot.

Sguyader: /* Processing time and memory use */

2017-11-20T00:10:33Z

Processing time and memory use

← Older revision		Revision as of 00:10, 20 November 2017
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	Two settings have a strong influence on resource use:		Two settings have a strong influence on resource use:
	• “Denoise” which adds around 1 sec. of processing time, and 1 MB of memory use;		• “Denoise” which adds around 1 sec. of processing time, and 1 MB of memory use;
	• “Global quality: Enhanced + chroma denoise” which adds around 0.5 sec. And 0.6 MB.		• “Global quality: Enhanced + chroma denoise” which adds around 0.5 sec. And 0.6 MB.
	These figures depend on the size of the RT-spot.		These figures depend on the size of the RT-spot.

Sguyader: /* Color and Light */

2017-11-20T00:10:04Z

Color and Light

← Older revision		Revision as of 00:10, 20 November 2017
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	===Color and Light===		===Color and Light===
	* The algorithms used for luminance and contrast in local mode differ from the ones used in “Lab adjustments”, which may lead to differences in rendering.		* The algorithms used for luminance and contrast in local mode differ from the ones used in “Lab adjustments”, which may lead to differences in rendering.
	* The luminance algorithm is made such that below -90 and down to -100 for “Lightness”, it is possible to increase the image's “darkness”, almost to the point of getting a luminance value close to 0. To accentuate this effect, “Chrominance” can be decreased and “Scope” increased.		* The luminance algorithm is made such that below -90 and down to -100 for “Lightness”, it is possible to increase the image's “darkness”, almost to the point of getting a luminance value close to 0. To accentuate this effect, “Chrominance” can be decreased and “Scope” increased.
	* The inverse mode can be used for creating graduated frames. If “Ligthness” is set to -100 and "Chrominance" is reduced, the “frame border” will be black.		* The inverse mode can be used for creating graduated frames. If “Ligthness” is set to -100 and "Chrominance" is reduced, the “frame border” will be black.

Sguyader: Add the information regarding the "excluding" RT-spot

2017-11-10T20:35:52Z

Add the information regarding the "excluding" RT-spot

← Older revision		Revision as of 20:35, 10 November 2017
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	It should be possible to replace the ellipse with a hand drawn curve (even if I think its usefulness is debatable because of the existence of the shape detection algorithm), as long as the homothetic transform of the curve doesn’t intersect with the original curve. Although the benefits from this intellectually satisfying “improvement” should negligible in the case of the RT-spots, it will be possible to make the current RT-spots and lasso type of controls coexist eventually.		It should be possible to replace the ellipse with a hand drawn curve (even if I think its usefulness is debatable because of the existence of the shape detection algorithm), as long as the homothetic transform of the curve doesn’t intersect with the original curve. Although the benefits from this intellectually satisfying “improvement” should negligible in the case of the RT-spots, it will be possible to make the current RT-spots and lasso type of controls coexist eventually.

			===The "normal" and "excluding" types of RT-spots===
			Two types of RT-spots are available:
			* "Normal": these are the spots which do the local retouching. Each new RT-spot takes into account the effect of existing spots when their zone of influence overlap (a sort of recursive action).
			* "Excluding": adding a new "excluding" RT-spot allows to revert the effect created by a "normal" RT-spot in their overlapping zone of influence , from the original image data (but doing its calculations from the reference values of the area affected by the "normal" RT-spot).

			For both types, the user has access to most of the modules ("Color and Light", "Contrast by detail levels", "Blur", ...)

			====Comments about the "excluding" RT-spot====
			* The principle of the "excluding" spot is similar to the "counterpoint" in Capture NX2, and is useful when for example, the effect of a "normal" RT-spot bleeds into an area which the user wants to be unaffected. This unwanted effect happens when when the tints of the two areas (the area the user wants to be affected, and the area one wants to remain unaffected) are to close.
			* The underlying algorithm is similar to the main algorithms used elsewhere in "locallab", and is based on tint differences. While it's not perfect it should give satisfaction 70% of the time.
			* I implemented an additional algorithm (with no guarantee that it will actually work one day) to help discriminate the areas, based on a Sobel-Canny transform. The transform is coded but is not yet accessible to the user, as I'm still working to make it more efficient.

			====How to use the "excluding" RT-spot, and its limitations====
			# Create a new RT-spot over the area you want to restore.
			# In the "Settings" panel, from the "Spot method" combobox choose "Excluding spot".
			# Adjust "Scope", "Transition" and "Spot size" as well as the shape of the zone of influence using the 4 handles, until you get the desired reversion of the effect. You can use complimentary adjustments such as "Color and light", etc.
			The algorithm computes the reference values (tint, chroma, luma) from the the current image (see below). As a consequence, the "excluding" effect won't work if the image area is black (for example when the user uses a normal RT-spot using "Color and light" in inverse mode to create a black frame).
			Sometimes, when the "inverse" mode is selected, the "excluding" spot algorithm may not work as expected and lead to a difference between the preview and the output (JPG, TIFF) image. Increasing the value of "Scope" of the "excluding" RT-spot should help in this situation.

	===Tint, chroma, luminance references and the algorithm principle in “normal” mode===		===Tint, chroma, luminance references and the algorithm principle in “normal” mode===

Keno40 at 16:04, 31 October 2017

2017-10-31T16:04:57Z

Jdc: /* Partitioning into 4 zones – previewing the RT-spot area */

2017-10-27T05:45:38Z

Partitioning into 4 zones – previewing the RT-spot area

← Older revision		Revision as of 05:45, 27 October 2017
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	* if "Show spot delimiters" is checked in "Preferences" > "General" tab > "Local adjustments", one can visualise approximately the area affected by the spot. Because I couldn’t work cleanly with the « arc/ellipse/scale » function in the Cairo graphics library, I made each quadrant defined by a pseudo-ellipse made of 3 Bézier curves joining each other. In most cases the approximation is satisfying… To help grabbing the 4 handles, I made them longer (the Bézier curves are inactive!).		* if "Show spot delimiters" is checked in "Preferences" > "General" tab > "Local adjustments", one can visualise approximately the area affected by the spot. Because I couldn’t work cleanly with the « arc/ellipse/scale » function in the Cairo graphics library, I made each quadrant defined by a pseudo-ellipse made of 3 Bézier curves joining each other. In most cases the approximation is satisfying… To help grabbing the 4 handles, I made them longer (the Bézier curves are inactive!).

	We obtain 4 zones, whose orientation ~~can~~ be modified (the default rotation angle is set to zero). Those 4 zones have each of their vertices connected by imaginary ellipses.		We obtain 4 zones, whose orientation cannot be modified (the default rotation angle is set to zero). Those 4 zones have each of their vertices connected by imaginary ellipses.

	It is possible to drag the handles outside the image preview area.		It is possible to drag the handles outside the image preview area.

Sguyader at 17:36, 26 October 2017

2017-10-26T17:36:30Z

Show changes

Sguyader: Created page with "==What kind of local control?== Several types of local control exist in mainstream applications : # “lasso”, associated with layers and fusion masks (e.g. Photoshop©)...."

2017-10-26T17:09:49Z

Created page with "==What kind of local control?== Several types of local control exist in mainstream applications : # “lasso”, associated with layers and fusion masks (e.g. Photoshop©)...."

Show changes

← Older revision		Revision as of 08:44, 18 July 2018
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	* the same principles which deal with luminance distribution – gamma sRGB – used in the main RawTherapee code.		* the same principles which deal with luminance distribution – gamma sRGB – used in the main RawTherapee code.

	Bear in mind that the automatic white balancing is a totally non deterministic mathematical problem. The algorithms may perform more or less well (and faster or slower), but a perfect result can’t exist! Why is it so? If one is referring to the principles of color management ([http://rawpedia.rawtherapee.com/Color_Management_addon/fr#Balance_des_blancs]), it is necessary to have knowledge of the three of: the ~~coloured~~ object, the illuminant and the observer. At least two of those are unknown in practice. In addition, the environment in which an image is shot is not known while it has an effect on the perception (CIECAM), and the same is true during both image editing and viewing. The mission is thus almost impossible!		Bear in mind that the automatic white balancing is a totally non deterministic mathematical problem. The algorithms may perform more or less well (and faster or slower), but a perfect result can’t exist! Why is it so? If one is referring to the principles of color management ([http://rawpedia.rawtherapee.com/Color_Management_addon/fr#Balance_des_blancs]), it is necessary to have knowledge of the three of: the colored object, the illuminant and the observer. At least two of those are unknown in practice. In addition, the environment in which an image is shot is not known while it has an effect on the perception (CIECAM), and the same is true during both image editing and viewing. The mission is thus almost impossible!

	The aim of the “White balance” module is '''for testing the algorithms''', there are 7 of them at least, and twice that number if “gamma sRGB” is considered. Indeed, in order to circumvent the obstacles encountered five years ago, instead of the using the image before demosaicing, I used the image just after demosaicing, allowing to apply (or not) “gamma sRGB”, ending in the same conditions as in normal use (but without normal “White balance” and “ICC or DCP” profile).		The aim of the “White balance” module is '''for testing the algorithms''', there are 7 of them at least, and twice that number if “gamma sRGB” is considered. Indeed, in order to circumvent the obstacles encountered five years ago, instead of the using the image before demosaicing, I used the image just after demosaicing, allowing to apply (or not) “gamma sRGB”, ending in the same conditions as in normal use (but without normal “White balance” and “ICC or DCP” profile).
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	Currently, RT-spots are operational in Lab mode with the following modules and methods:		Currently, RT-spots are operational in Lab mode with the following modules and methods:
	# ~~“Colour~~ and Light”: “Lightness”, “Chrominance”, “Contrast” in normal mode with 4 curves L=f(L), L=f(H), C=f(C), H=f(H), and in “inverse” mode;		# “Color and Light”: “Lightness”, “Chrominance”, “Contrast” in normal mode with 4 curves L=f(L), L=f(H), C=f(C), H=f(H), and in “inverse” mode;
	# “Exposure”: normal mode only;		# “Exposure”: normal mode only;
	# “Vibrance:” normal mode only;		# “Vibrance:” normal mode only;
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	* For each quadrant, depending on the the value of the “Scope” slider, the algorithm does:		* For each quadrant, depending on the the value of the “Scope” slider, the algorithm does:
	# take into account the tint difference between the zone centre and the affected pixel;		# take into account the tint difference between the zone centre and the affected pixel;
	# through a complex algorithm based on the deltaE notion (perceived difference between two ~~colours~~, taking tint, chroma and luminance into account), decrease the amount of applied effect as a function of the difference between the central zone and the affected pixel;		# through a complex algorithm based on the deltaE notion (perceived difference between two colors, taking tint, chroma and luminance into account), decrease the amount of applied effect as a function of the difference between the central zone and the affected pixel;
	# follow either a linear or a parabolic law to adjust the amount of applied effect, based on the specific the case.		# follow either a linear or a parabolic law to adjust the amount of applied effect, based on the specific the case.

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	# a correction is made (with threshold and iterations) in order to avoid correcting (or only slightly, based on the user’s choice) the grey or neutral tones which are in the same tint as the reference (but with a low chroma value);		# a correction is made (with threshold and iterations) in order to avoid correcting (or only slightly, based on the user’s choice) the grey or neutral tones which are in the same tint as the reference (but with a low chroma value);
	# the parameters are weighted based on the shape of the RT-spot (ellipses) and the transition zone;		# the parameters are weighted based on the shape of the RT-spot (ellipses) and the transition zone;
	# the values of the “Global quality:” parameters are important, particularly so for images with a low amount of noise – chroma noise is interpreted by the algorithm being of the same ~~colour~~ as the spot. It is thus necessary to suppress this noise, that is the purpose of “Enhanced + chroma denoise” (this algorithm may not be sufficient, though – in this case using the local “Denoise” module may be useful).		# the values of the “Global quality:” parameters are important, particularly so for images with a low amount of noise – chroma noise is interpreted by the algorithm being of the same color as the spot. It is thus necessary to suppress this noise, that is the purpose of “Enhanced + chroma denoise” (this algorithm may not be sufficient, though – in this case using the local “Denoise” module may be useful).

	This new (“super”) algorithm seems to perform generally well, but in the event when the RT-spot is located in a grey/neutral or flat area, the algorithm may fail. In such cases, using the old algorithm is recommended (except for “Retinex”, “Tone Mapping” and “Contrast by detail levels” for which it is made unavailable for the sake of code simplicity).		This new (“super”) algorithm seems to perform generally well, but in the event when the RT-spot is located in a grey/neutral or flat area, the algorithm may fail. In such cases, using the old algorithm is recommended (except for “Retinex”, “Tone Mapping” and “Contrast by detail levels” for which it is made unavailable for the sake of code simplicity).
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	===Avoid color shift===		===Avoid color shift===
	The “Avoid color shift” checkbox serves two purposes:		The “Avoid color shift” checkbox serves two purposes:
	* put the ~~colours~~ within the current working profile gamut, using a relative colorimetry;		* put the colors within the current working profile gamut, using a relative colorimetry;
	* adjust ~~colours~~ using a “Munsell” correction – particularly for red-orange and blue-purple ~~colours~~, when saturation in the Lab* space has changed significantly.		* adjust colors using a “Munsell” correction – particularly for red-orange and blue-purple colors, when saturation in the Lab* space has changed significantly.

	===“mip” files – Principles of the multi-point algorithm===		===“mip” files – Principles of the multi-point algorithm===
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	===Tone Mapping===		===Tone Mapping===
	Caution when uniformly ~~coloured~~ areas (sky, grey/neutral zones) have a similar tint to the area on which the RT-spot is placed. In cases where this leads to artefacts, set the “Iterations” slider to 0 in “Settings” > “Reduce artefacts – Improve algorithm”.		Caution when uniformly colored areas (sky, grey/neutral zones) have a similar tint to the area on which the RT-spot is placed. In cases where this leads to artefacts, set the “Iterations” slider to 0 in “Settings” > “Reduce artefacts – Improve algorithm”.

	===Retinex===		===Retinex===
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	* an additional “Chroma” slider.		* an additional “Chroma” slider.

	Caution when uniformly ~~coloured~~ areas (sky, grey/neutral zones) have a similar tint to the area on which the RT-spot is placed. In cases where this leads to artefacts, set the “Iterations” slider to 0 in “Settings” > “Reduce artefacts – Improve algorithm”.		Caution when uniformly colored areas (sky, grey/neutral zones) have a similar tint to the area on which the RT-spot is placed. In cases where this leads to artefacts, set the “Iterations” slider to 0 in “Settings” > “Reduce artefacts – Improve algorithm”.

	===Denoise===		===Denoise===

← Older revision		Revision as of 16:04, 31 October 2017
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	Several types of local control exist in mainstream applications :		Several types of local control exist in mainstream applications :
	# “lasso”, associated with layers and fusion masks (e.g. Photoshop©). This kind of control is widespread (Photoshop, Gimp, Darktable…) and users tend to favor those, at the expense of the type ~~desciribed~~ in 3. below, which is less well known;		# “lasso”, associated with layers and fusion masks (e.g. Photoshop©). This kind of control is widespread (Photoshop, Gimp, Darktable…) and users tend to favor those, at the expense of the type described in 3. below, which is less well known;
	# dedicated tools for the removal of image defects such as “red eyes”, or “spots” associated with sensor imperfections or dirt;		# dedicated tools for the removal of image defects such as “red eyes”, or “spots” associated with sensor imperfections or dirt;
	# “U-points” controls, used until recently in Nikon Capture NX2©, or as an add-on to other software such as Nik Software©. For those (rare now) who tried such programs, there’s no way turning back to layers and fusion masks! This type of local control requires learning something different, and a cognitive “reprogramming”. In my opinion, this kind of local control is globally more efficient.		# “U-points” controls, used until recently in Nikon Capture NX2©, or as an add-on to other software such as Nik Software©. For those (rare now) who tried such programs, there’s no way turning back to layers and fusion masks! This type of local control requires learning something different, and a cognitive “reprogramming”. In my opinion, this kind of local control is globally more efficient.
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	In order to improve manipulation and avoid long menus on screen, I added a GUI interface which is similar to the one used in the Wavelet tab, with “expanders”. Thus for each module (“Color and Light”, “Blur”, “Retinex”, …) you can choose to:		In order to improve manipulation and avoid long menus on screen, I added a GUI interface which is similar to the one used in the Wavelet tab, with “expanders”. Thus for each module (“Color and Light”, “Blur”, “Retinex”, …) you can choose to:
	# display (or not) the full list of commands: sliders methods, curves…		# display (or not) the full list of commands: sliders methods, curves…
	# activate (or not) ~~the~~ all the functions of the module.		# activate (or not) all the functions of the module.

	Warning: choice 2. activates or cancels all the RT-spots~~; it~~ would be possible in theory to add this capability to every single RT-spot, but for what purpose?		Warning: The second choice activates or cancels all the RT-spots. (It would be possible in theory to add this capability to every single RT-spot, but for what purpose?)

	===Lab and RGB local controls===		===Lab and RGB local controls===
	* The first algorithms are coded in Lab* mode with the following modules: “Color and Light”, “Blur / Add noise”, “Retinex”, “Tone mapping”, “Sharpen”, “Contrast by Detail Levels”, “Denoise”. Two additional modules have been added: “Exposure” and “Vibrance”.		* The first algorithms are coded in Lab* mode with the following modules: “Color and Light”, “Blur / Add noise”, “Retinex”, “Tone mapping”, “Sharpen”, “Contrast by Detail Levels”, “Denoise”. Two additional modules have been added: “Exposure” and “Vibrance”.
	* See below for the principles of the different algorithms, but one key point to remember for shape detection and ~~artifacts avoidance~~, is that the Lab mode preserves the “hue” tint, which is crucial.		* See below for the principles of the different algorithms, but one key point to remember for shape detection and artifact limitation, is that the Lab mode preserves the “hue” tint, which is crucial.
	* The idea of an “RGB” module comes to one’s mind, with ''a minima'':		* The idea of an “RGB” module comes to one’s mind, with ''a minima'':
	** a “White balance” module, which would allow to locally adjust the white balance, for example to warm up shadows, or to deal with mixed scene lighting such as “daylight” and “tungsten”. This module needs to be inserted just after “demosaic”.		** a “White balance” module, which would allow to locally adjust the white balance, for example to warm up shadows, or to deal with mixed scene lighting such as “daylight” and “tungsten”. This module needs to be inserted just after “demosaic”.