| Author | Message | ||
     Bruce Bodine Member Username: Bbodine9 Post Number: 47 Registered: 09-2005 |
From the tutorial it states: 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. 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. What is start tone "b" ? Thanks ! | ||
| den Member Username: Den Post Number: 273 Registered: 03-2006 |
Whatever you want it to be! For replacing clipped r, b, or g channel highlights, 'b' could equal 90% thereby masking channel image areas that comprise the 90->100% tone range so that you could do channel substitutions.... ...or... A lot of times for two peak histogram images with significant sky and foreground image areas and you want only to isolate the sky, 'b' could be the lowest dip between the two peaks... usually somewhere around 65%, thereby masking image areas that comprise the 65->100% tone range so that you could substitute a different sky... ...or... Perhaps you have a single peak histogram image and you would like to enhance contrast of the lower mid-tones through the highlights to emphasize existing captured ambient subject lighting, the 'b' could 40%, thereby masking image areas that have 40->100% tones, so that when a darkening contrast HSV,V curve, for example, is used, the shadow and upper shadows are not affected... ...etc, etc... By using the Mask Tool - Brightness Curve Probe and perhaps changing the Histogram resolution to 'High' from the OPT dropdowns, one can be fairly precise [not always necessary] in choosing a value for 'b'. For using a tone range mask to isolate an image area, one can also 'lower-left' Apply a preliminary ADD curve and see if it covers the intended image area, if not, simply 'Undo' and 'lower-left' Apply an ADD curve with a different 'b', repeat as necessary until acceptable, then proceed with the Blur, SUBTRACT curve, and +/-2 Feathering. Any of the tone range masks [hightlight, shadow, and mid-tone] are: (1) image content dependent; (2) dependent upon the purpose to which the mask is to be used; and (3) manually selected/determined by the post-processor. One needs to become comfortable with understanding how an image's histogram relates to its content, highlight, mid-tones, and shadow image areas... ...this comes with practice and this type of post-processing is a highly enjoyable and rewarding way to spend a rainy day with a cup of coffee nearby and soft jazz/light classics on the studio stereo! | ||
| den Member Username: Den Post Number: 274 Registered: 03-2006 |
In the previous posting, only 'b' was discussed in terms of a 'highlight tone range mask' used by itself for varying purposes but 'a' should be mentioned as well because when all of the '3Tone Range masks' are used in a workflow, it is intended the 'a' and 'b' remain the same during a specific workflow iteration where: (1). The 'a' designation refers to the shadow tone range end tone and the mid-tone range start tone and is the horizontal control point curve value for the associated ADD and SUBTRACT curves.... and (2). The 'b' designation refers to the mid-tone range end tone and the highlight tone range start tone and is the horizontal control point curve value for the associated ADD and SUBTRACT curves.... For perhaps a better understanding and an appreciation for PWP, take a look at this, Luminosity Masks, a tutorial for a PhotoShop CS approach for PWP's '3Tone Range Masks and Procedures' keeping in mind the following: (1). Read the text information and do not closely try to understand or follow the program steps/dialog settings... but do look at the illustrations for original and preview image comparisons when shown. (2). Tone Range Masks are derived from the 'luminosity' channel rather than PWP's Mask Tool - Brightness Curve (HSV,V). (3). Towards the end of the tutorial, there is a series of masks for each of the Highlight, Mid-tone, and Shadow tone ranges... these are nothing more than differing 'a's and 'b's used in a PWP workflow iteration. (4). Illustrated curve changes are performed in the RGB color space, where PWP offers the additional options of the HSV and HSL color spaces... and if PWP's ColorCurves transform is used, HSV,S and HSL,S saturation changes are readily available as well as for tone [HSV,V or HSL,L]. (5). The PhotoShop CS tone range masks tend to be lower in contrast than the PWP '3Tone Range Masks' and so there is less chance of objectionable and noticeable halos or tone reversals... the downside is that a particular tone range change is more conservative and not as aggressive as what may be achieved in a PWP workflow although there is artistry required to select a Blur in PWP to prevent halos and tone reversals. Where PS user's tend to rely on small programmed 'actions' or 'plug-ins'... PWP's strength is to let you know 'what's under the hood!'... ...of course this begets 'understanding'... ;-) |
