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Inverted Masks, Masked Luminosity Painting, Blurred Masks

June 14, 2012

In a previous post I described how luminosity painting is one of my favorite techniques for balancing the light in an image. The technique can be effectively used to burn or dodge specific parts of an image while maintaining tonal contrast in the areas being painted. In this post I’ll expand on the technique a little more and show some variations in the procedure that can be useful.

Unlike black and white images where a full tonal range from delicate whites to detailed shadows is often desirable, color images usually look better with the highlights retaining some good color instead of going to light or pure white. In fact, I’ve developed a preference for a left-shifted histogram for color images–no whites at all and mostly composed of mid-tones and quarter tones as seen in the histogram below.

Histogram

Even though there may not be many of them in an image, getting the brightest values correct is still important. This is difficult to do sometimes because simply darkening white values yields gray, which really has no color either, and doesn’t contribute to the richness that may be desired. A good place to start to achieve the proper light tones is with RAW conversion, making sure there are no clipped highlights and that the light tones are already left-shifted and retaining color. This allows them to be further developed to the proper brightness and contrast in Photoshop.

The image below is one that I consider nearly finished. Color, brightness, contrast, and saturation had been addressed during processing, and on-screen it seemed nearly as good as I could make it. I usually let the print help make the final call as to when an image is actually finished, and the light values in this image looked a little weak in the print. They had too much tonal whiteness and not enough color richness. The rollover of the image (it may take a few seconds to load) shows the final version after the light tone had been further addressed. These tones have been darkened in the rollover and have richer color, but the contrast in these light values has been retained to bring out the texture.


There are, of course, many ways luminosity masks could be used to make this adjustment. What I’ll illustrate here is a way to do it with a combination of techniques, each of which may also be useful in other situations.

INVERTED MASKS

The first thing that will be done is to luminosity paint through an inverted luminosity mask. I’ve previously written that these inverted masks aren’t too useful. They tend to include a lot of tones and don’t isolate specific tones as a result. However, there is a dictum with luminosity masks that point to a way in which inverted masks might be useful:

To increase contrast in an image when luminosity painting, paint white through a Lights-series mask or paint black through a Darks-series mask.

Because of the way luminosity masks are generated, each series concentrates the selection progressively towards one end of the tonal spectrum. The Lights-series masks, for example, have fewer and fewer tones as the masks progress from Lights to Light Lights to Bright Lights and finally to Super Lights. The tones that do remain in the progression are the whitest and lightest with pure white being selected in every mask. Luminosity painting through a Lights-series mask, therefore, deposits more paint on the less-masked light tones than on the relatively more-masked darker tones. So painting with white means that the light tones get more paint and get lighter faster than the darker tones, which receive less paint. The end result being increased contrast in the area being painted. The opposite happens when painting with black through a Lights-series mask—the less-masked light tones receive more black paint and darken faster than the more-masked darker tones, which in turn decreases contrast in the area being painted.

Any inverted mask switches to the opposite series. An inverted Light Lights mask, for example, is effectively a Darks-series mask. Even though the inverted mask doesn’t have a name, it’s character is decidedly that of a Darks-series mask, namely that the parts of the image that show in the mask are a gray-scale negative of the original image with the darkest tones being 100% pure white in the mask. This is demonstrated in the Light Lights mask for the above image which is shown below. The rollover shows the Darks-series inverse.


So according to the dictum, painting black through the inverted Lights Lights selection, which becomes a Darks-series selection, should darken and increase contrast in the areas that receive paint. That’s what was done in this case. The process is as follows:

  1. Create the Burn/Dodge layer (new layer > fill with 50% gray > set blending mode to “Soft Light”)
  2. Create a Light Lights selection (and save a copy as a mask on the Channels panel).
  3. Invert the selection.
  4. Hide the marching ants.
  5. Make sure the foreground color is set to black.
  6. Paint black onto the Burn/Dodge layer through the inverted Light Lights selection (a 33% opacity soft brush was used)
  7. Deselect the hidden selection when done.

After luminosity painting through the inverted Light Lights mask, the Burn/Dodge layer looked like the image below. The areas darker than 50% gray cause darkening in the image.

Luminosity-painted layer

The resultant image is shown below. The too-light areas have been made darker and painting through a luminosity mask has blended the darkening into the rest of the image, but it’s overdone. There is now a blackness in some of the areas that were painted as well as some dark haloing along the center ridge. This is because the broad, inverted selection allowed the paint to be applied in a very imprecise manner. Too much black paint reached the darker pixels in the image because they are substantially revealed by the inverted selection. While this is expected, the image has taken on a color “gloppiness” as a result. For reference, the rollover is the original image.


It may be hard to notice, but within this heavy-handed paint job the desired darkening of the light tones has been achieved along with a slight boost in their overall contrast. Black paint applied through a Darks-series mask (the inverted Light Lights in this case) insures this. Now it’s just a matter of fine-tuning the painting to separate the properly-painted pixels from the poorly-painted ones.

MASKING LUMINOSITY PAINTING

A luminosity layer mask on the luminosity-painted Burn/Dodge layer is the way to reveal the good parts of this bad paint job. Interestingly, the Light Lights mask, the one that was inverted for luminosity painting, can now serve as the correct mask to reveal the desired darkening in the pixels that were originally too light. While simply adding the Light Lights mask as a layer mask does a pretty good job, I prefer to actually paint the mask through the Light Lights selection so as to create a more precise reveal and to augment it with multiple brush strokes in specific areas. The procedure is as follows.

  1. Create a Hide All layer mask on the Burn/Dodge layer (a “black” layer mask).
  2. Create a Light Lights selection. (NOTE: It’s best to use the original Light Lights mask from the unpainted image instead of creating a new one from the now gloppy image. The original Light Lights mask can be stored on the Channels panel when it’s created and reselected at this point.)
  3. Hide the marching ants.
  4. Make sure that the mask is selected for painting and that white is the foreground color.
  5. Paint white onto the layer mask (100% opacity, soft brush) in the areas where the darkening effect of the luminosity painting needs to be revealed.
  6. Deselect the hidden selection when done.

Imprecision in painting this time has a much less deleterious effect on the image. The Light Lights selection is much narrower than its tonal inverse. As such, it’s harder to paint outside the lines because the selection is more confining as to where paint gets applied. Some care needs to be taken in smaller confined areas or where multiple brush strokes are used, but overall a few wide strokes of the brush creates the painted mask that reveals the darkening in just those areas where it’s needed. The remaining dark areas of the painted mask effectively conceal the gloppiness of the original paint job. Below is the painted mask that was created. The whitest areas are where multiple brush strokes were applied to create greater reveal of the luminosity painting.

Painted mask

The image that results after painting the layer mask for the Burn/Dodge layer is shown below. The rollover is the unmasked layer with the gloppy luminosity painting that was visible without the layer mask.


The painted mask effectively selected the right pixels to reveal in order to achieve the desired darkening effect in the light tones of the image. This is a good example of how luminosity mask selections, when employed in painting, can correctly select tones and seamlessly blend the desired effect into the rest of the image. What’s most remarkable in this case is that even after the grossly overdone luminosity painting through the inverted mask, painting a layer mask through the Light Lights selection was still able to reveal just the right amount of tonal adjustment for each pixel that received paint and almost effortlessly facilitated the desired adjustment to the image.

The blue highlighted layer below shows how this Burn/Dodge luminosity painting layer with its painted layer mask looked in Photoshop’s Layers panel when the procedure was complete.

Layers panel

BLURRING THE MASK

While I don’t often feel it necessary to blur luminosity masks, this is one time that it helped. Light tones tend to blend together visually. Blurring the mask provides a bit of increased sharpness, which causes what texture there is in the light tones to become a bit more visually separated. When I apply blur to luminosity masks, it’s usually a 21-pixel Gaussian blur. That amount was chosen to “correlate” with my 21-megapixel camera, but I’m not really sure if there is any correlation at all. For whatever reason, the 21-pixel Gaussian blur seems to provide a good result when used to blur a luminosity mask. The blurred mask is shown below.

Layers panel

Below is the final image after the blur was applied to the layer mask. The rollover is the image with the unblurred layer mask. The difference may be hard to see in this size image, but it has a nice effect on a larger jpeg and the actual print.


In summary, three steps were used to make this adjustment:

  1. Paint through an inverted luminosity mask to maintain/enhance contrast.
  2. Create a painted layer mask by painting through a luminosity mask selection to reveal the luminosity painting to the appropriate degree in the appropriate pixels.
  3. Blur the layer mask if it helps to improve textures/contrast.

If you’d like to practice this technique on this image, a larger version with a prominent copyright symbol is available for download here.

4 Comments leave one →
  1. June 15, 2012 12:11 pm

    Another great tutorial. Thank you

    Antonio

    PS: what is “Auto PF correction layer” in the pallet?

    Like

    • June 15, 2012 8:08 pm

      The “Auto PF correction layer” is a Photoshop action to remove purple fringing. I bought mine years ago from a friend and have carried it forward with every new computer and version of Photoshop. It does an excellent job of removing purple fringing that is sometimes obvious in areas of light-dark contrast. I think it works great and will sometimes duplicate the layer produced by the action to enhance the effect a bit more if need be. Google suggests you can purchase it at: http://www.clipclip.org/ky1008/clips/detail/7320. I didn’t purchase mine here, so I can’t vouch for the site, but the actions author is Shay Stephens, so that looks legit, and the price was $10, so that matches too.

      Like

  2. October 8, 2013 3:30 pm

    Tony,

    Does inverting the Light Lights channel simply result in the Dark Darks channel?

    Like

    • October 14, 2013 4:06 pm

      No. While the Lights and the Darks selections are the inverse of each other, the rest of the selections in the “Lights” and “Darks” series are not the inverse of each other. Instead, the rest of the masks in each series are derived from the initial Lights or Darks masks through selection intersection (or multiplication).

      Like

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