Gina - Skin Tone Correction

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A plug-in for the camera RAW image processing program Bibble.
Author: Sean Puckett (seanmpuckett@gmail.com).

Bibble 5 note: This is a Bibble 4 plug-in. It does not work with Bibble 5.

What does Gina do?

Gina is dedicated to correction and enhancement of skin tones, especially the reduction or elimination of reddish blotches that make people look unnatural in prints. GinaPRO also provides tools to change skin colour and saturation, to make skin tones more uniform, and to apply a sharpening/blurring filter to skin tones only. GinaPRO can also add noise to skin tones to mask overly smoothed skin, and has a glow function that subtly elevates skin tones, adding an inner life to portraiture that is very difficult to capture without perfect studio lighting

Download Freeware Now

Gina Freeware is available for download now, and includes just the "blotch fixer" portion of GinaPRO.

Windows, Linux and Mac versions included in the same download. Read the Gina Release Notes, then access the download area.
You'll find installation instructions as INSTALL.txt in the zipfile.
Please provide feedback at the email address above.

Purchase Professional Version Now

Windows, Linux and Mac versions included in the same download. GinaPRO is now available for Windows, Macintosh (Intel and PPC), and Linux. GinaPRO has many more features than the basic Gina, and allows much greater control of selection.

GinaPRO: $20 USD

Already purchased, but need an upgrade? Click Here.

If you purchase this plug-in, you do so knowing it is not compatible with Bibble 5. I do not provide installation support for Bibble 4 plug-ins, and in purchasing them you do so at your own risk. Further, I do not guarantee that any Bibble 4 plug-in will be available for Bibble 5.

Sample Output

Here's our sample image. It's a nice shot, but unusable because of skin tone issues. For starters, there's a ghastly green reflection from the sunlit grass. My wife's fair complexion has been shot through with red blotches from the reflected infrared. And it's just plain hard to see her face.

GinaPRO Off Info

Here's GinaPRO's fixup -- it just took half a minute or so to find the settings to get this effect -- the green reflections are neutralized, the red blotches have been toned down, her skin tone has been lightened up and sharpened, and saturation backed off just a little to reduce the bright reflections.

GinaPRO On Info

And these same settings can be copied to all the other shots in this set (dozens!), cleaning up the skin tone just the same way with just a tweak here or there. That's what GinaPRO can do for your portrait photography.

User Interface and Method of Operation

GinaPRO 1.0 Info

Gina first fixes problem skin (blotch fixer, if enabled), then adjusts all skin tones. If your subject has overly red cheeks or skin blemishes or other areas that don't match up with their overall skin tone, you should first fix the blotches with the blotch fixer. Once the blotch fixer is finished, the rest of Gina (the skin adjuster) takes over. Keep this in mind -- first fix blotches, then adjust all skin tones.

To Select Skin for Modification

You use three sliders to select skin: Hue A, Hue B, and Feather. Hue A and B select the starting/ending hues that represent the range of skin tones you want to change. Feather softens the outer boundary of this range to keep changes less noticable. Hue is chosen in degrees around the colour circle, with 0 degrees being pure red. In general, human skin tones are centered around 15 degrees, although different complexions have different hues. The defaults for the Fixer hue sliders are set to capture most blotchy skin colours (from 0 to 10). The defaults for the Adjustment hue sliders are set to capture average skin tones (from 10 to 20). You can adjust these sliders within a very large range.

  1. Turn on the "see selection" checkbox. The image will black out all pixels that are not selected.
  2. Adjust Hue A and Hue B so only skin tones you want to change are visible. The brighter a pixel, the more "selected" it is.
  3. Adjust Feather, if needed, to soften or harden the selection.
  4. Make your adjustments (the see selction checkbox will turn off automatically).
  5. If you see hard edges in your image, increase the feathering.
  6. If unwanted colours are being changed, change the Hue sliders to include less colours.

GinaPRO, unfortunately, cannot operate by allowing you to just click on parts of the image to select them as skin -- Bibble's UI makes it impossible for plug-ins to access the mouse in this fashion.

If you're still getting too much (or not enough) skin selected, use the additional selection sliders to fine-tune luminance criteria:

  • White point - Changes the maximum luminance accepted. Sometimes useful for clearing teeth and the whites of eyes. If you decrease this too much, highlights will drop out.
  • Black point - Changes the minimum luminance accepted. Sometimes useful for clearing darker hair tones. Increase it too much, and shadows will drop out.
  • Lum Soft - Feathers the white/black point slider selections.

And saturation criteria:

  • Sat Max - changes the maximum saturation accepted. Useful for clearing strong reds in the background or clothing, and sometimes lips.
  • Sat Min - changes the minimum saturation accepted. Useful for clearing teeth, whites of eyes, and off-white backgrounds.

GinaPRO User Interface

Enable Checkbox

When checked, the plug-in can affect the image. When unchecked, disables the plug-in.

Reset Button

Resets all plug-in values to startup defaults. Useful for getting back to a sane place after experimenting wildly.

? Button

Reveal the plug-in version number, author and homepage.

Blotch Fixer Group

The blotch fixer is dedicated to correcting small areas that stand out as unwanted skin tone. Generally you'll use this to reduce the appearance of overly red skin due to infrared reflections or to disguise skin blemishes.

Hue A, Hue B and Feather Sliders

These sliders adjust which skin tones are identified as "blotchy" and need to be fixed. See the section above "To Select Skin for Modification" on how to use these sliders. The Blotch fixer doesn't allow you to adjust saturation or luminance selections as they're already preset for most blotch fixing purposes.

Shift Slider

Shifts the hue of selected blotch tones. Move to the right (generally) to remove redness. The Blotch fixer also applies a moderate amount of "gather" (see below) but there is no way to adjust how much (it didn't seem necessary).

Skin Selection Group

These sliders select the range of pixels affected by the Skin Adjustment group, below. See the section above "To Select Skin for Modification" on how to use them. Gina's selection algorithm provides feathering for saturation and luminance as well as hue, providing a reasonably wide selection area that focuses on the most likely tonal values of skin; the feathering amounts are not adjustable through the UI (how many sliders do we really need, anyway?!).

Skin Adjustment Group

Saturation Slider

Adjusts the saturation (colour intensity) of skin tones. Generally you won't need to mess with this unless you've got camera or exposure or conversion problems. Still, a little bit (0.1 or so) can help someone who's looking pale.

Shift Slider

Adjusts the overall skin tone. 99% of the time, you'll move this slider to the right, not the left. Left adds red, right subtracts it. Move this slider one "click" at a time -- click to the right of the pointer. Don't just grab it and haul it over to 1.0, unless the "embalmed" look pleases you.

Gather Slider

At the midpoint between Hue A and Hue B is the "centrepoint" of the skin tone range. As you increase Gather, all colours within the range are moved proportionally closer to the centrepoint, making skin tones more uniform. If you reduce gather below 0, colours are moved farther away from the centrepoint, enhancing tone variability.

Soft/Shrp Slider

The filter applies a sharpening (positive values) or softening (negative ones) to skin tone pixels only. Gina is very good about only altering skin and leaving other things (like jewellry and clothing) unchanged.

Noise Slider

Noise adds a measured amount of gaussian monochromatic noise to skin tones. This is helpful to add back the high frequency noise (texture) that aggressive smoothing can eliminate. In other words, if your skin tones look like plastic, either ease up on the softening filter, or try and mix in some noise.

Glow Slider

This is a fancy trick -- it adds subtle amounts of light to the shadow tones of skin. At higher values, it increases the overall brightness of skin tones. Visually, it acts as if someone was shining a light through your subject's skin, making it look brighter than it would from just reflected light. It can really make simple portraits look lush. If you drag the slider below 0, you'll remove illumination, but there isn't much use to this that I can identify.

Notes

Gina Freeware not compatible with GinaPRO

The settings used by Gina Freeware are not compatible with GinaPRO settings. Nevertheless, you can't have both GinaPRO and Gina Freeware installed at the same time.

No Guarantee that GinaPRO can fix every image!

I'm really pushing the boundaries of what can be done in a plug-in as far as selective colour work goes. I cannot promise you that GinaPRO will be able to do exactly what you want on every image. It may select too much, not enough, leave blotches, or just not work well at all.

All I can offer is an assurance that it for me and for the testing team (four full-time photographers who work extensively in portraiture and/or weddings), GinaPRO works exceptionally well on a vast majority of images, does okay on many more, and should probably not be used on a few. I'm not trying to be a weasel, I'm just want you to know that there is no Bibble-based panacea for great skin tone in every shot you take. If you need to drop to photoshop for a few images -- that's better than using photoshop on all of them.

Why can't I see anything happening?

Are you sure? Did you click the Enabled checkbox off and on several times? Gina's effects are subtle unless you go crazy with the sliders. Retouching should not be noticable except in A/B comparisons. If you think Gina isn't working, move the sliders to their extremes and you should see an effect. Then back them down slowly until you find a pleasing skin tone. Still, I think it's better to start from zero and adjust upwards so you find the minimum effect that works, rather than the maximum effect that is tolerable.

There's another possibility, though -- if the white balance of your picture is so far off that skin doesn't fall in the normal colour range for well balanced skin, Gina won't think your subject's skin is "skin." Solution: white balance your photo again. If this doesn't help, or if you like the skin tones the way they are, then Gina isn't going to work on that shot. Try HueyPRO instead -- it's more complex and fiddly, but can change any colours.

How does GinaPRO compare to Huey and HueyPRO?

While Gina uses the same technology those plug-ins use, it's been enhanced and simplified to do one thing very well. Gina's three sliders control the effects of what in HueyPRO would take the careful adjustment of three tabs (M,R,Y) worth of correction -- and these adjustments are integrated together in Gina, wheras in HueyPRO they're less correlated to allow more flexibility. Gina even offers sensitivity to luminance, something that HueyPRO does not, due to additional UI overhead, so there is functionality in Gina that currently cannot be reproduced in any other tool.

Does Gina affect other colours?

Gina can affect other colours in your image -- particularly ones that look like skin, but also the more saturated reds that Gina mistakes for blotchy skin. As long as Gina's effects are subtle on skin, they'll probably be subtle on the rest of the image as well. And in most cases where you want to use Gina, the colours of anything else in the picture are nowhere near as important as the colour of skin -- so your approach should be: fix the skin. No one who hasn't seen the original will notice changes to other skin-like tones.

Argh! Tiny little blotches are everywhere!

It happens sometimes when you are working with images with lots of sensor noise and out-of-focus elements. This is because the image is made up of lots of tiny areas of very different colour, only some of which match Gina's definition of "skin." The problem is most noticable when you use the Glow slider -- so take it easy on Glow when dealing with high ISO and somewhat blurry exposures.

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