Hugin Exposure tab - Revision history

Thomas at 17:30, 30 January 2013

2013-01-30T17:30:20Z

Thomas at 17:29, 30 January 2013

2013-01-30T17:29:29Z

Harryvanderwolf at 13:42, 30 January 2013

2013-01-30T13:42:05Z

Harryvanderwolf: Replaced content with "As explained on the Hugin Photos tab hugin has a brightness and colour correction system using the default non..."

2013-01-30T13:15:18Z

Replaced content with "As explained on the Hugin Photos tab hugin has a brightness and colour correction system using the default non..."

Bruno: use only images selected in preview moved from preferences

2008-04-12T16:21:00Z

use only images selected in preview moved from preferences

Bruno: /* Low dynamic range */

2008-02-27T23:23:37Z

‎Low dynamic range

Bruno: /* Camera Response */ typo

2007-06-20T20:31:52Z

‎Camera Response: typo

Pablo: /* Vignetting Centre */ independent of d&e

2007-06-20T11:45:05Z

‎Vignetting Centre: independent of d&e

Bruno: some more stuff on optimising exposure

2007-06-11T22:00:40Z

some more stuff on optimising exposure

Bruno: correction

2007-06-11T20:41:00Z

correction

← Older revision		Revision as of 17:30, 30 January 2013
Line 70:		Line 70:
	Keep '''Link''' checked to ensure '''hugin''' applies the same		Keep '''Link''' checked to ensure '''hugin''' applies the same
	response curve to all photos with the selected lens number.		response curve to all photos with the selected lens number.
		+
		+
		+	[[Category:Software:Hugin]]

@@ Line 2: / Line 2: @@
 Hugin comes with an extended set of predefined settings for photometric optimisation. If these predefined options do not give the desired results you can define your custom parameters in this '''Hugin Exposure tab'''.
 = Photometric Optimisation =
 == Image variables ==

← Older revision		Revision as of 13:42, 30 January 2013
Line 1:		Line 1:
−	As explained on the [[Hugin Photos tab#Photometric_.28Simple_User_interface.29\|Hugin Photos tab]] hugin has a brightness and colour correction system using the default nona stitching tool.	+	As explained on the [[Hugin Photos tab#Photometric_.28Simple_User_interface.29\|Hugin Photos tab]], hugin has a brightness and colour correction system using the default nona stitching tool.

−	Hugin comes with an extended set of predefined settings for photometric optimisation. If these do not ~~gice~~ the desired results you can define your custom parameters in this '''Hugin Exposure tab'''.	+	Hugin comes with an extended set of predefined settings for photometric optimisation. If these predefined options do not give the desired results you can define your custom parameters in this '''Hugin Exposure tab'''.
		+
		+	= Photometric Optimisation =
		+
		+	== Image variables ==
		+	In the '''Image variables''' part of the screen you can modify the exposure EV, the ''red multiplier'' '''Er''' and the ''blue multiplier'' '''Eb'''.
		+
		+	The '''Red multiplier''' and '''Blue multiplier''' settings are used to account for changes
		+	in '''white balance''' (also known as ''colour balance'' or ''colour temperature'') between
		+	photos. Setting them both to ''1'' will result in no ''white balance'' change (the numbers
		+	are relative to the green channel which stays unaltered).
		+
		+	As with exposure, different photos in the same project are quite likely to require different
		+	''white balance''. Typically this will be caused by variations in lighting conditions between
		+	shots - For example a cloudy scene will contain considerably less ''red'' light than the same scene
		+	under direct sunlight.
		+
		+	== Camera and Lens variables ==
		+	The values that you can change in the '''Camera and Lens variables''' table is again dependent on the '''Simple''', '''Advanced''' or '''Expert''' User interface.
		+
		+	=== Vignetting ===
		+
		+	[[Vignetting]] is dependent mainly on your lens and the ''aperture''. Usually the
		+	centre of the image is brighter with a falloff towards the edges. The three
		+	numbers here represent a polynomial curve used by [[hugin]] to correct vignetting.
		+
		+	You are not expected to guess these values, they are generally loaded with a lens
		+	profile or calculated from two or more overlapping photos.
		+
		+	Set the values to ''0,0,0'' for no vignetting correction.
		+
		+	Usually all photos taken with the same ''lens'' will have the same vignetting, keep
		+	'''Link''' checked to ensure '''hugin''' applies the same vignetting correction to all
		+	photos with the selected lens number.
		+
		+	=== Vignetting Center Shift ===
		+
		+	The centre of [[vignetting]] is rarely the exact centre of the photo. The two numbers
		+	here indicate the position of the vignetting centre. The scale is in pixels, with
		+	''0,0'' indicating the centre of the photo. The values are independent of the '''d'''
		+	& '''e''' parameters which specify the origin for projection and geometric distortion.
		+
		+	<!-- As with other lens parameters, this '''Vignetting Center Shift''' can be optimised in
		+	the [[hugin Exposure tab]]. Keep '''Link''' checked to ensure [[hugin]] applies the same
		+	vignetting centre to all photos with the selected lens number. -->
		+
		+	=== Camera Response ===
		+
		+	The [[camera response curve]] is used both for mapping the images to a linear
		+	colourspace when creating [[HDR]] output, and for normalising the colourspace
		+	for internal vignetting, brightness and colour corrections when creating
		+	'normal' '''LDR''' output.
		+
		+	[[hugin]] uses the [http://www1.cs.columbia.edu/CAVE/projects/rad_cal/rad_cal.php EMoR response model]
		+	from the Computer Vision Lab at Columbia University which simplifies the full
		+	response curve to these five empirical coefficient numbers. You are
		+	not expected to guess these values, they are generally loaded with a lens
		+	profile or calculated from two or more overlapping photos.
		+
		+	Set the five numbers to ''0,0,0,0,0'' to use a generic response curve or change the '''Type'''
		+	to '''Linear''' to indicate that your input photos have a ''scene-referred'' or [[HDR]]
		+	response.
		+
		+	Keep '''Link''' checked to ensure '''hugin''' applies the same
		+	response curve to all photos with the selected lens number.

@@ Line 1: / Line 1: @@
-[[hugin]] has a brightness and colour correction system which is completely
+As explained on the [[Hugin Photos tab#Photometric_.28Simple_User_interface.29|Hugin Photos tab]] hugin has a brightness and colour correction system using the default nona stitching tool.
-independent of the old [[PTStitcher]] tool.  This improved system is only
-available with the default [[nona]] stitching tool in the [[hugin Stitcher tab]].
-The '''hugin''' system works by sampling a spread of points for each pair of
+Hugin comes with an extended set of predefined settings for photometric optimisation. If these do not gice the desired results you can define your custom parameters in this '''Hugin Exposure tab'''.
-overlapping images.  The optimiser then tries to model a system of [[camera response curve]],
-'''exposure''', '''white balance''' and [[vignetting]] that fits the values of these points.
-−
-So for this to work, the photos in the project have to be already aligned.  Align
-photos by managing control points in the [[hugin Control Points tab]] and optimising
-geometric image parameters in the [[hugin Optimizer tab]].
-−
-'''Only use images selected in preview.''' allows you to work with just a few
-of the images in the current project rather than all of them.  Use the buttons along the top of the
-[[Hugin Preview window]] to enable and disable source photos.  When optimising, all the hidden images will be ignored.
-−
-== Optimize Preset ==
-−
-Use the '''Optimize Preset''' combo box to pick one of several pre-set photometric
-optimisation schemes, then click the '''Optimize now!''' button to calculate the
-best available brightness and colour adjustments.
-−
-=== Low dynamic range ===
-−
-This will optimise [[vignetting]], the [[camera response curve]] and '''exposure''' (EV)
-for all the photos in your project.
-−
-The exposures for all images (except for the anchor image determined by selecting
-'''Anchor this image for exposure''' in the [[hugin Images tab]]) are optimised.
-−
-=== Low dynamic range, variable white balance ===
-−
-This will optimise [[vignetting]], the [[camera response curve]], '''exposure''' (EV) and
-'''white balance''' for all the photos in your project.
-−
-Similarly to above, the exposures and white balance is optimised for all images except the
-''anchor''.
-−
-=== High dynamic range, fixed exposure ===
-−
-This will optimise [[vignetting]] and [[camera response curve]] for all photos.
-−
-=== High dynamic range, variable white balance, fixed exposure ===
-−
-This will optimise [[vignetting]], the [[camera response curve]] and '''white balance'''
-for all the photos in your project.
-−
-=== Custom parameters below ===
-−
-The pre-set options are good for most situations, but often it is necessary to switch to
-'''Custom parameters'''.  For example, none of the pre-sets will optimise the
-'''Vignetting Centre''', so use custom parameters if your vignetting is off-centre.
-−
-== Image Variables ==
-−
-Image variables are quite likely to vary between photos, perhaps because of minor
-variations in shutter speed, changes in natural light or because of 'auto' settings
-in the camera itself.
-−
-=== Exposure ===
-−
-The '''Exposure''' section shows the photo number and exposure values for all input
-photos (in parenthesis), the check mark indicates parameters that will be optimised.
-−
-When a value is set to ''0'' (zero) this results in [[hugin]] applying no exposure
-change to the photo.  ''EV'' is a standard photographic scale, each increase or
-decrease by one unit will change the exposure by the equivalent of one ''f-stop''
-(ie. halving or doubling the exposure).
-−
-=== White balance ===
-−
-Also known as ''colour balance'' or ''colour temperature''.
-−
-The '''White balance''' section shows the photo number and ''red'' and ''blue''
-multiplier values (in parenthesis), the check mark indicates photos that
-will be optimised.  If the values are set to ''(1,1)'', this will result in no
-'''white balance''' change (the numbers are relative to the green channel which
-stays unaltered).
-−
-== Camera and Lens variables ==
-−
-The '''Camera and Lens variables''' are the ''photometric'' analog of the ''geometric'' [[lens correction model]], [[hugin]]
-assumes that all input photos with the same '''lens number''' have identical values unless they are '''unlinked''' in the
-[[hugin Camera and Lens tab]].
-−
-=== Vignettting ===
-−
-[[Vignetting]] is dependent mainly on your lens and the ''aperture''.  Usually the centre of the image is
-brighter with a falloff towards the edges, [[hugin]] can calculate this falloff curve as part of the
-''photometric optimisation'' process or you can enter it manually in the [[hugin Camera and Lens tab]]
-as the three numbers shown here.
-−
-=== Vignetting Centre ===
-−
-The centre of [[vignetting]] is rarely the exact centre of the photo,
-[[hugin]] can optimise this position or you can enter it manually in the
-[[hugin Camera and Lens tab]].  The scale is in ''pixels'', with ''0,0''
-indicating the centre of the photo. The values are independent of the
-d & e parameters, that specify the origin for projection and distortion
-values.
-−
-=== Camera Response ===
-−
-[[hugin]] can optimise the [[camera response curve]] by comparing differences
-between overlapping images. To do this your photos need to either have
-significant [[vignetting]] or have variable exposure.  If your photos have
-perfectly even exposure and zero vignetting, then you would have to
-calibrate the camera response separately and then enter it manually in the
-[[hugin Camera and Lens tab]].
-−
-The '''camera response curve''' is used both for mapping the images to a linear
-colourspace when creating [[HDR]] output, and for normalising the colourspace
-for internal vignetting, brightness and colour corrections when creating
-'normal' '''LDR''' output.  If your pictures don't require such corrections
-then you don't really need a calibrated response curve.
-−
-Hugin uses the [http://www1.cs.columbia.edu/CAVE/projects/rad_cal/rad_cal.php EMoR response model]
-from the Computer Vision Lab at Columbia University which simplifies the full
-response curve to five empirical coefficient numbers.
-−
-If your brightness variations are caused by lens flare then you may be better not optimising
-'''Exposure''' or '''white balance''', instead uncheck '''Link''' for '''Camera Response'''
-in the [[hugin Camera and Lens tab]] to optimise a different response curve for each photo.
-−
-__NOTOC__
-[[Category:Software:Hugin]]

@@ Line 10: / Line 10: @@
 photos by managing control points in the [[hugin Control Points tab]] and optimising
 geometric image parameters in the [[hugin Optimizer tab]].
 == Optimize Preset ==

@@ Line 24: / Line 24: @@
 The exposures for all images (except for the anchor image determined by selecting
 '''Anchor this image for exposure''' in the [[hugin Images tab]]) are optimised
-(TODO actually the anchor is too?).  Though by default all images with the same ''lens number''
+(TODO actually the anchor is too?).
-are assumed by [[hugin]] to have the same exposure, so if you actually want to
-optimise '''exposure''' separately for each photo, then uncheck '''Link''' for '''Exposure (EV)'''
-in the [[hugin Camera and Lens tab]].
 === Low dynamic range, variable white balance ===
@@ Line 35: / Line 32: @@
 Similarly to above, the exposures and white balance is optimised for all images except the
-''anchor''.  By default all images with the same ''lens number'' are assumed by [[hugin]]
+''anchor''.
-to have the same exposure and white balance, so uncheck '''Link''' for '''Exposure (EV)''',
-'''Red multiplier''' and '''Blue multiplier''' in the [[hugin Camera and Lens tab]].
 === High dynamic range, fixed exposure ===