3Tone Range Adjustment Procedures, Masks, and Workflows
Introduction:
. . .Update for PWP3.5.0.10 / PWP4x / PWP5x Users. . .
The '3Tone Range Adjustment Procedures' as presented below were written when PWP3.1.h was the latest PWP version. Since then, there have been minor changes to the editing transforms/tools and the addition of PWP RAW conversion. The suggested techniques are still applicable with these later PWP versions for the purposes of 'tone mapping' to preference specific image areas selected on the basis of the gray tones that they contain with the following qualifications/equivalencies:
1. PWP RAW Conversions:
The '3Tone Range Adjustment Procedures' work best for images that have near 'full range' [0 to 100% or 0 to 255 tones] and near final adjustment for brightness, contrast, and color. Camera download jpeg image files where the RAW conversion takes place in the camera and image parameters such as exposure, contrast, sharpness, saturation, tone, WB, etc., have been applied are such images. Non-PWP RAW converters that allow these image parameters to be preferentially applied are also such images.
PWP RAW conversion is unique in that essentially no image parameters become part of the resulting conversion image file, especially if 'No Expansion' is selected. For the 'No Expansion' PWP RAW conversion image, it is suggested that an initial expansion to near full range; and adjustments for brightness, contrast, and color be performed similar to Step1 of 'A RGB Brightness Curve with Mask Approach' prior to performing the '3Tone Range Adjustment Procedures'.
2. Equivalancies:
Mask Tool: PWP31h 'Apply' = PWP3.5/4x/5x 'lower-left' Apply
Mask Tool: PWP31h 'Log Histogram' = PWP3.5/4x/5x 'High Histogram Expansion'
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This is a 'Picture Window Pro' [PWP] 'capture toning' adjustment workflow that will preserve and heighten highlight and shadow image details that would normally be de-emphasized when only globally applied mid-tone range brightness, contrast, and saturation changes are performed. 'Complex tone range masks' are used to separate the image's tones into ranges for enhancement. This mask isolates a selected range of tones from all others in the image, effectively creating an 'image within an image' where its black/white points, brightness, contrast, and saturation can be changed without generally creating unacceptable halos or changing tones outside the selected range.
Definition of terms:
- Capture toning - initial adjustments of brightness, contrast, and saturation of an image with near full tone range, brightness, contrast, and saturation such as camera download jpegs, non-PWP RAW conversions, and scanned images with scanner processing applied. Note: 'No Expansion' PWP RAW conversion images need adjustments similar to Step1 of 'A RGB Brightness Curve with Mask Approach' to have near full tone range, brightness, contrast, and saturation.
- Creative toning - secondary adjustments of brightness, contrast, and saturation to specific image areas needed to meet image concept objectives, normally subsequent to 'Capture toning'.
- Creative enhancement - 'Creative toning' plus color balance, color correction, noise reduction, and sharpening to meet image concept and output objectives.
- Tone range mask - a mask whose white, grays, and black areas allow changes only to image areas that contain the selected range of tones. Depending upon edge boundary transitions [grays], these tone range masks can easily generate halos and auras. Their transition zones [grays] are generally symmetrical radiating from a 50% gray tone.
- Complex tone range mask - a 'Tone range mask' that has differing gradient rates of change and width from a 50% gray tone in the transition zone to white and black. The gradient from 50% gray to white is soft and wide; and the gradient from 50% gray to black is hard and short. Consequently, these tone range masks do not easily generate halos/auras and are generally un-useable if 'inverted' due to being asymmetrical radiating from a 50% gray tone.
- Image area mask - a mask whose white, grays, and black areas allow changes to all tones and colors contained in the selected image areas.
- Transition zone mask - a "...mask of a mask's..." gray tones that separates the first mask's black and white image areas for use to fine adjust blending and/or de-emphasize halos.
- Output - presentation and display media format: album, web, print, etc.
These procedures can be used whole or in part depending upon the image and the results desired.
For example: (1) a neutral density filter effect may be achieved if only the highlight tone range [range expanded to include all of the sky/cloud tones to a ridgeline or sea horizon with near/mid-distance objects that extend above the ridgeline/sea horizon subtracted] procedure is applied to an image that has significant sky and clouds; (2) significant changes to highlights and/or shadows while leaving the mid-tones unaffected can be achieved using their appropriate workflow(s) less the mid-tone procedures; (3) changes to mid-tones with expanded or contracted ranges can be made without affecting the original highlights and shadows using only the mid-tone procedures; and (4) landscape or seascape images especially benefit when the complete '3Tone Range Adjustments' are made.
The tone ranges, color spaces, curves, and transform amounts are suggested starting points. Be sure to experiment and change to best suit the image:
- The initial Highlight Tone Range adjustments are suggested to take advantage of HSL color space characteristics [colors reach 100% saturation at their 50% grey tone value] as generally the highlight tones have low saturation and as the contrast is increased by darkening, the colors become more saturated. This works well to bring out cloud details and increases sky colors.
- The suggested [12,20] control point of the Shadow Tone Range brightening/contrast curve is the point at which the curve crosses the 20% vertical tone value when a [50,50] control point is moved to [50,60]. Additionally, increasing both brightness and contrast in the HSV color space with the Brightness Curve transform works well to bring out details [color and lower mid-tones] in large dark areas of the image.
- Initial mask blur amounts are suggested where they are 25->35% of the pixel width of the largest masked tone area before blurring.
- For especially 'vivid' saturations for mid-tones, try making changes in the RGB color space.
While all this may seem overly complicated, it really isn’t. All that is happening is that an image is divided into three parts by the selected tone ranges; and then each of the parts is optimized for brightness, contrast and saturation. The results can be dramatic and need only a small amount of sharpening applied after any Color Balance and/or Color Correction changes.
Creating a Complex Highlight Tone Range Mask: Generically, a complex 'highlight tone range mask' for a range of b->100% tones is formed by the following steps. An explanation of the significance of these steps may be found here. Mask and transform curve designations and formation are explained here. Considerations for the selection and use of 'a' and/or 'b' are suggested here.
- Open or click on an image, and open the Mask Tool - Brightness Curve option.
- Use the Probe to determine the needed range start tone, b.
- ADD SMOOTH CURVE = [0,0], [b,0], [b+10,100], [100,100] where b is the beginning tone.
- Apply Blur = 25->35% of the pixel width of the largest masked tone area before blurring, usually
50->100 for a highlight tone range.
- SUBTRACT SMOOTH CURVE = [0,100], [b-20,100], [b,0], [100,0]
- Apply Feather = - 2
- Apply Feather = +2
- Leave mask 'active' by clicking on the 'applied' image and then open a transform or click OK, creating a BW 8-bit mask image file. For maximum mask effectiveness, check its dynamic range in the Levels & Color transform and expand to full range if necessary [precludes the 'active' mask workflow option].
An 80->100% Complex Highlight Tone Range Example:
Step 1A: Create a mask of the 80->100%
highlight tones using the Mask Tool - Brightness Curve where the ADD curve = [0,0], [80,0], [90,100], [100,100]; Blur somewhere between 50->100; SUBTRACT curve = [0,100], [60,100], [80,0], [100,0]; and Apply -/+ 2 Feather. [An example workflow of a typical 'complex tone range' mask shown for shadows is here.]
Note: If the image does not have full tone
range to 100%, then add the needed % tone range to the 80->100% range mask in
1.A above. For example, if the image’s highest tone is 92%, then add 8% to the 80-100% range mask, i.e., masking 72->100% and in the Brightness Curve transform [HSL color space], move the [100,100] control point left to 92%.
The mask's ADD +10/100 curve slope, Blur, SUBTRACT -20/100 curve slope, and -/+2 Feather; create a transition buffer to the unaffected parts of the image and helps minimize objectionable halos and auras as well as posterization. Check to see if the created mask has full dynamic range with the Levels and Color transform, as high amounts of blurring will usually result in a less than full dynamic range mask. A full dynamic range mask is desired in order to give the maximum amount of adjustments with a transform's black and white sliders.
Step 1B: Using the Brightness Curve transform with the Highlight Range mask, add a control point at [50,50] and move it to between [50,40] and [50,30] while in the HSL or HSV color space. Anything outside this range of adjustment seems to posterize the image to gray tones but don’t be afraid to experiment. If the highlight tones become too saturated [clouds take on an unnatural cast] instead of using the Brightness Curve transform, use Color Curves where the L or V curve is adjusted as previously described and the S curve has an added [50,50] control point moved to between [50,50] and [50,40] to decrease saturation. The transform mask amount settings are usually white=50->100 and black=0 assuming an un-inverted mask.
Note: If the image does not have full highlight tone, then
relocate the [100,100] point left until it does. Be sure to temporarily switch from Linear to Log Histogram with the OPT drop downs to verify that needed highlights are not being clipped. A fuller explanation is here.
Step 1A and Curve 1B
Shadow Tone Range: A range of tones that includes black [0% or 0 tone value] as its start tone.
Creating a Complex Shadow Tone Range Mask: Generically, a complex 'shadow tone range mask' for a range of 0->a% tones is formed by the following steps. An explanation of the significance of these steps may be found here. Mask and transform curve designations and formation are explained here. Considerations for the selection and use of 'a' and/or 'b' are suggested here.
- Open or click on an image, and open the Mask Tool - Brightness Curve option.
- Use the Probe to determine the needed range end tone, a.
- ADD SMOOTH CURVE = [0,100], [a-10,100], [a,0], [100,0] where a is the end tone.
- Apply Blur = 25->35% of the pixel width of the largest masked tone area before blurring, usually
10->35 for a shadow tone range.
- SUBTRACT SMOOTH CURVE = [0,0], [a,0], [a+20,100], [100,100]
- Apply Feather = - 2
- Apply Feather = +2
- Leave mask 'active' by clicking on the 'applied' image and then open a transform or click OK, creating a BW 8-bit mask image file. For maximum mask effectiveness, check its dynamic range in the Levels & Color transform and expand to full range if necessary [precludes the 'active' mask workflow option].
A 0->20% Complex Shadow Tone Range Example:
Step 2A: Create a mask of the 0->20% shadow tones using the Mask Tool - Brightness Curve where the ADD curve = [0,100], [10,100], [20,0], [100,0]; Blur somewhere between 10->35; SUBTRACT curve = [0,0], [20,0], [40,100], [100,100]; and Apply -/+ 2 Feather. [An example workflow of a typical 'complex tone range' mask shown for shadows is here.]
Note: if the image does not have full tone range to 0%, then before performing Step 2A, expand the image to 'full range' in HSV color space with the 'Levels & Color' transform or if there is a shadow color cast, use the 'full range' OPT-ion of the 'Color Balance' transform in the RGB color space.
The mask's ADD -10/100 curve slope, Blur, SUBTRACT +20/100 curve slope, and -/+2 Feather; create a transition buffer to the unaffected parts of the image and helps minimize objectionable halos and auras as well as posterization. Check to see if the created mask has full dynamic range with the Levels and Color transform, as high amounts of blurring will usually result in a less than full dynamic range mask. A full dynamic range mask is desired in order to give the maximum amount of adjustments with a transform's black and white sliders.
Step 2B: Using the Brightness Curve transform with the Shadow Range mask, add a control point at [12,20] while in the HSV color space. Move the [100,100] control point to the left until halos/auras just appear. This occurs somewhere around [70,100]. You can then leave this point here and then adjust the [12,20] control point minutely left or right for best contrast detail. Or you could decide to reduce the blur on the mask. This would allow you to move the [100,100] control point further left for more dramatic contrast in the shadow areas. Try to adjust the mask blur so that the [100,100] control point can be between [40,100] and [50,100] without objectionable halos/auras or noise. Again remember to adjust the [12,20] control point left or right for best contrast details to show. This adjustment may be so small that you will need to expand the curve window to give you the needed degree of control over this control point’s relocation. If this produces too much shadow noise, then move the [40,100]->[50,100] control point slightly to the right to lessen contrast. The transform mask amount settings are usually white=38->100 and black=0 assuming an un-inverted mask.
Step 2A and Curve 2B
Mid-Tone Tone Range: A range of tones that excludes black [0% or 0 tone value] and white [100% or 255 tone value].
Creating a Complex Mid-Tone Tone Range Mask: Generically, a complex 'mid-tone range mask' for a range of a->b% tones is formed by the following steps. An explanation of the significance of these steps may be found here. Mask and transform curve designations and formation are explained here. Considerations for the selection and use of 'a' and/or 'b' are suggested here.
- Open or click on an image, and open the Mask Tool - Brightness Curve option.
- Use the Probe to determine the needed range start tone, a, and end tone, b. If either a Shadow Tone Range Mask and/or a Highlight Tone Range Mask have been used, then use the 'a' and/or 'b' determined for those mask(s).
- ADD SMOOTH CURVE = [0,0], [a,0], [a+10,100], [b-10,100], [b,0], [100,0] where a is the start tone and b is the end tone.
- Apply Blur = 25->35% of the pixel width of the largest masked tone area before blurring, usually
35->65 for a mid-tone tone range.
- SUBTRACT SMOOTH CURVE = [0,100], [a-20,100], [a,0], [b,0], [b+20,100], [100,100]
- Apply Feather = - 2
- Apply Feather = +2
- Leave mask 'active' by clicking on the 'applied' image and then open a transform or click OK, creating a BW 8-bit mask image file. For maximum mask effectiveness, check its dynamic range in the Levels & Color transform and expand to full range if necessary [precludes the 'active' mask workflow option].
Note: If the selected tone range [a<20, b>80] precludes either one or both of the 20/100 SUBTRACT curve slopes, just do the best available. For a narrow tone range where (b-a)<40, a single mid-point control point for the ADD curve can be used, i.e., use [(a+b)/2,100] instead of the [a+10,100] and [b-10,100] curve control points.
The mask's ADD +/-10/100 curve slopes, Blur, SUBTRACT -/+20/100 curve slopes, and -/+2 Feather; create a transition buffer to the unaffected parts of the image and helps minimize objectionable halos and auras as well as posterization. Check to see if the created mask has full dynamic range with the Levels and Color transform, as high amounts of blurring will usually result in a less than full dynamic range mask. A full dynamic range mask is desired in order to give the maximum amount of adjustments with a transform's black and white sliders.
A 20->80% Complex Mid-Tone Tone Range Example:
Step 3A: Create a mask of the 20->80% shadow tones using the Mask Tool - Brightness Curve where the ADD curve = [0,0], [20,0], [30,100], [70,100], [80,0], [100,0]; Blur between 35->65; SUBTRACT curve = [0,100], [20,0], [80,0], [100,100]; and Apply -/+ 2 Feather. [An example workflow of a typical 'complex tone range' mask shown for shadows is here.]
Step 3B: Using the Brightness Curve transform in either the HSV or RGB color space with the Mid-Tone Range mask, add two control points, [30,30] and [70,70]:
- For no mid-tone brightening or darkening: move the [30,30] control point to [30,20]; move the [70,70] control point to [70,80]; and adjust the mask's white amount to a preference.
- For mid-tone brightening: move the [70,70] control point to [70,80] and adjust the mask's white amount to a preference.
- For mid-tone darkening: move the [30,30] control point to [30,20] and adjust the mask's white amount to a preference.
The transform mask amount settings are usually white=38->100
and black=0 assuming an un-inverted mask. The suggested curve here has a slightly "s" shape to increase contrast. Try these changes in both the HSV and RGB color spaces; picking the one that most pleases. Changes in the RGB color space usually result in more 'vivid' saturations then those produced using the HSV color space.
Step 3A and Curve 3B [No mid-tone brightening or darkening shown]
Comments and Application Guidelines:
This will generally complete the image’s 'capture toning' adjustments. There may be an image specific feature that would need further attention. This is masked off with an 'image area mask' and adjusted further as needed.
Not all images need changes to each of the three tone ranges: highlights, shadows, and mid-tones. If two or more of the tone range procedures are to be applied, the suggested sequence of application is in order of the largest image area masked by a selected tone range to the smallest image area masked by a selected tone range. In the case of landscapes/seascapes, optimizing the highlights, then shadows, and then mid-tones seems to work best, especially using a highlight tone range mask for the sky/clouds and adjusting brightness, contrast, and saturation in the HSL color space.
It is generally best in the case of the application of more than one tone range adjustment, that the selected tone ranges do not overlap each other, i.e., 'a' or 'b' are not changed between adjoining tone ranges: Highlight to Mid-tone and Shadow to Mid-tone. It is also possible to have 'a' = 'b', where the a Shadow and a Highlight tone range adjoin. Here these tone range masks are used in the place of a 'contrast mask' and are referred to as '2Tone Range Adjustments'. Considerations for the selection and use of 'a' and/or 'b' are suggested here.
The Color Curves transform is used in place of the Brightness Curve when adjustments to saturation are desired in addition to brightness and contrast changes. While hue can also be changed using the Color Curves transform, better 'fine' control and selectivity are available using the Color Correct transform.
Until an understanding of moving the black and white points in either the Brightness Curve or Color Curves transform is reached, it is best to expand an image to 'full range' first in either the Levels and Color or Color Balance transform before starting the '3Tone Range Adjustment Procedures'.
Usually this tone range adjustment approach will be very effective in bringing out details so that a reduced amount of globally applied 'local contrast enhancement' or 'LCE' should be considered, if used.
Again, the results of these procedures are often dramatic and need only a slight amount of USM sharpening applied after any Color Balance and/or Color Correction changes and 'LCE', if used.
The real challenge [and artistry] comes into play when selecting tone ranges and transforming the desired changes with the masks so that no objectionable halos and/or auras are created in the unaffected image areas.
References:
The following sources had influence on the ideas and terminology contained herein:
- J. Sach's white paper: 'Creating and Using Masks', on page 35, 'Creating density masks' discusses highlight, mid-tone, and shadow image tone separations.
- G. Mitchell's 2004 tutorial on Luminous Landscape, 'Masking by the Numbers'.
- B. Fraser's article, pg 2, 'Out of Gamut: Thoughts on a Sharpening Workflow'.
Image Examples:
The following is a cropped 4x6 ratio, Canon S45, large, super-fine '24-bit color' jpeg image file download where the in-camera picture settings for contrast, sharpness, and saturation were 'normal'; and camera settings for exposure and white balance were 'Evaluative' and 'Auto':
Camera Download Image. (c) IMAGEs by DEN 2004
'3Tone Range Adjustment Procedures' were applied: (1) Highlight Range: sky/clouds and mountains expanded to 100% white with sea gull and drift wood arms subtracted; (2) Shadow Range: drift wood shadows; and (3) Mid-Tone Range: foreground beach, water, mid-distance buildings/trees, drift wood, and sea gull. Color Balance and Color Correction were applied followed with global USM [amt=25, r=2, thrsld=0]
sharpening. Clicking on the image will link to a partial 'Highligh tone range' workflow.

Three Tone Range Adjusted Image. (c) IMAGEs by DEN 2004
A 'Shadow and Lower Mid-Tone Recovery' with two different workflows using the same 'complex shadow tone range' mask can be seen by clicking on the following image, a Canon S45 jpg 24 bit color download file:

1Tone Range adjustment required to recover Shadow and Lower Mid-Tones. (c) IMAGEs by DEN 2005
A detailed workflow for a Canon 20D, minimally RAW converted camera download image requiring the use of two 'complex tone range' masks, one for highlights and one for shadows in its workflow can be seen by clicking on the following image:

2Tone Range adjustments required for 'capture' toning. A CS image - used with permission.
A detailed workflow where PWP's Filter transform is used to simulate an image's over and under exposures for extending apparent 'dynamic range' and then used to also add sun dappeling as a 'creative' effect can be seen by clicking on either of the following images:
Extending apparent tone range and sun dappeling. (c) IMAGEs by DEN 2005
You are welcome to see other IMAGEs by DEN.