Siggy - Exposure Control

Plug-In News and Updates
Subscribe to my RSS feed or bookmark my blog to stay informed.

Bundles Available!
Save money when buying plug-in bundles! Click any purchase link to learn more.

A plug-in for the camera RAW image processing program Bibble.
Author: Sean Puckett (

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

What does Siggy do?

Siggy is an exposure adjusting tool that gives you easy control over your image's luminance (a.k.a. brightness). Unlike many traditional "brightness" or "exposure" sliders, Siggy attempts to preserve detail in highlights and shadows even when greatly increasing or decreasing overall luminance. Siggy also allows you to enhance contrast subtly or dramatically, and lets you adjust shadow and highlight tones with their own specific sliders.

Download Freeware Now

Siggy is available for download now.

Windows, Linux and Mac versions included in the same download. Read the Siggy 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 SiggyPRO Professional Version Now

Windows, Linux and Mac versions included in the same download. SiggyPRO is the professional version of Siggy, and gives you extra controls for additional adjustments of your image. SiggyPRO adds two new sliders: "Shadow Range" and "Highlight Range" which alter the luminance levels that the base "Shadows" and "Highlight" sliders affect. With these sliders, you can restrict shadows/highlights to just a very small range of tones, or your entire image. This gives you more possibilities for correcting severe defects, or just applying more creative control.

SiggyPRO: $10 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

Siggy Bird Before Info

Siggy Bird After Info

Minor Adjustments

This well exposed but somewhat "blah" shot just needed a little punch. Brightess up just a tad, shadows pulled down a bit, and the barest bit of contrast. Perhaps too much -- but Siggy allows experimentation, so you get to decide what you like best.

Siggy Car Before Info

Siggy Car After Info

Major Corrections

A well composed shot suffering from a bit of underexposure. Siggy raises the brightness without making the highlights totally blown out and allows a little bit of contrast compression to help neutralize the glare from an unfortunate lack of a polarizing filter. Pulling up the shadows gives some extra detail under the car and in the background.

Siggy LV Before Info

Siggy LV After Info

Tough Shot Rescue

This shot of the Las Vegas skyline is a nightmare. While the heavy afternoon haze of the summer desert sun is causing everything in the distance to be washed out, the foreground foliage is nearly silhouetted.

Siggy saved the shot, though, adding contrast to the mountains, raising the shadow zone up at least a stop, and giving the whole image a much needed "haze reduction." And, unfortunately, revealing a little bit of sensor dust. Deserts do that. Sigh.

Siggy Flowers Before Info

Siggy Flowers After Info

Massive Contrast

Siggy opens up new avenues of artistic exploration as this high contrast conversion shows. Most controls are gentle near 0, but can get quite extreme near the outer limits. Go wild -- see what you can create.

"Before" shots taken with Siggy disabled, "After" shots taken with Siggy enabled -- no other changes to Bibble's settings occurred.

All images Copyright 2006 Sean M. Puckett. All rights reserved.

User Interface

SiggyPRO 1.1 Screenshot Info

Note the screenshot to the right is of SiggyPRO and includes the Shadow/Highlight Range sliders. Siggy (free version) doesn't have these sliders but otherwise looks the same.


The enable checkbox controls whether Siggy's settings affect the image. By clicking the checkbox off and on, it is easy to see the effect Siggy contributes to the image.


Clicking the reset button forces all of Siggy's sliders to neutral effect.

? Button

Click this to get the version number, author and homepage URL of the plugin.


Bright operates on its own, adjusting overall image brightness. Image brightness is adjustable from -2 to 2, where 0 is "no change." Positive values make the image brighter overall, negative values make it darker. Use the mouse wheel to tweak brightness in amounts of 0.01 per detent.

Extreme brightness adjustments can result in clipped blacks or whites, and should be used with caution to achieve special effects.

Contrast and Midpoint

Contrast and Midpoint work together to adjust the image contrast. Each slider is adjustable from -1 to 1, with the mouse wheel allowing fine adjustment of 0.01 per detent. The Midpoint slider works only to the degree of Contrast added -- if there is very little contrast change, the midpoint slider will have little effect.

The contrast slider adjusts the degree of contrast applied. 0 means "no change." Positive contrast values emphasise image contrast, negative values reduce it. Contrast values near 0 have a very small effect to allow fine adjustments; values near 1 and -1 affect the image profoundly to permit artistic experimentation.

The midpoint slider alters the "centre" of the contrast effect. As you move the midpoint slider, the lightness of the image that has the most response to the change in contrast moves. This is difficult to explain in words; for the most useful explanation of what midpoint does, set the contrast slider to 0.8 or more, then adjust midpoint. You should see immediately how it works -- a low midpoint centers the contrast effect on darker image values, high midpoint on lighter image values.

Shadow and Highlight

These two controls affect extremely dark and light values of your image respectively. Both controls will allow quite high levels of adjustment, and can alter absolute white & black somewhat in the "lighter shadows" or "darker highlights" direction. Similarly, extreme values of "darker shadows" and "lighter highlights" can result in loss of shadow or highlight detail to absolute black or white. Use care with these sliders and monitor the histogram for feedback if this is important.

Saturation Compensation

Siggy operates on the image in Lab colour space, and works primarily with the L luminance channel. Significant changes in luminance can alter the saturation of colours when the image is converted to working colour space. Siggy can correct for this using different algorithms and amounts of correction depending on your needs.


Enables/disables saturation compensation.


Controls the compensation algorithm used.

  • Film - Film compensation essentially re-exposes the image at the new luminance levels, adjusting saturation levels to correspond to how those luminance levels would have photographed if they were originally lit at that brightness. Extremely bright and dark luminance levels will re-expose to very low saturation, as would film.
  • Linear - Linear compensation alters saturation directly in proportion to change in luminance. Adding more luminance (brighter) = more saturation (more colour).


The amount of compensation applied, from 0 (no compensation) through 1 (full compensation) to 2 (extreme compensation) according to your desire. Remember that this doesn't adjust total saturation -- 0 will not make your image black and white. It adjusts how much Siggy changes saturation for the change in luminance it makes.


Here are some tutorials on using Siggy to accomplish some common image problems and special effects.

Siggy Tutorials
Siggy Tutorial: BW "Blowout" Portrait
Siggy Tutorial: Raccoon Eyes fix


Thoughts about using Siggy that I've had during the course of its development.

Order of Operations

Siggy's equations proceed from top-to-bottom on the control panel. Brightness first, then contrast, then shadows, then highlights. You should approach Siggy in that order, too. First ajust Bright to fix exposure, then use Contrast/Midpoint to fix emphasis, then tweak Shadow and Highlight detail. If you've perfected a contrast setting and then adjust brightness, your midpoint will be wrong because you moved all of the image tones around.

Fix big things first, then move on to little tweaks.

Using Contrast & Midpoint to help Fix Lighting Problems

The midpoint control is particularly useful when adjusting contrast of skintones and faces, which are often the most important part of an image. To locate midpoint correctly, choose an exaggerated contrast of 0.8 or more, then adjust the midpoint so the contrast effect "splits" the skintones into light & dark. This helps you visualize where the contrast effect will be most prominent. Then return the contrast control to values near zero and perfect your image.

Raccoon eyes: If your subject has harsh shadows, perhaps the dreaded "raccoon eyes" of a mid-day sunlit portrait, a midpoint-adjusted contrast can help. Find the midpoint between lit skin and shadowed skin as described above, then adjust the contrast to -0.20 to -0.10 and see if you can help bring the lit/unlit flesh tones a little closer in brightness. Not too much -- remember that the whole image will be affected by this -- but even a little bit helps. If that's still not good enough, you're just going to have to fire up Photoshop.

Flat lighting: Similarly, flat lighting caused by total overcast or shooting in the shade can be helped, too. Again, find the midpoint in the skintones (gently, this time, there's not much distance), then choose a slightly positive contrast between 0.10 and 0.20 to emphasise what shadows are there. Subtle changes are best -- use the "enabled" checkbox to compare. If the image looks "fixed" you've gone too far!

Recovering Highlights and Shadow Detail

Bibble's highlight recovery does great things in pulling detail out of your RAW files, but once the data's been recovered, often it just sits there at the top of your histogram looking very much like white. Siggy's Highlight control is great at bringing that lost detail down range where it can actually be seen. Tweak it downwards gently to reveal skin texture lost in blowouts, or clouds in the sky. If there's anything there at all, even one step away from pure white, Siggy can bring it down where you can see it.

Similarly, if you think you've lost details the the shadows, punch up the shadow slider and see what you can find. I've been surprised many times at what I thought was an ocean of black was full of textures that, while not richly coloured, could still be used to add more detail where you might have settled for nothing.

Data has to Go Somewhere

Siggy is a "holistic" image adjuster. Every control, even shadow and highlight, affects the entire image. This is because when room is made at one brightness level for "more contrast" or "extra highlight detail," it's got to come from somewhere. So if you look carefully, you'll notice in the histogram that when you pull down highlight detail, most of the rest of your image moves down, too, although in a subtle fashion. All of the Siggy sliders work this way, and remember the effect. You don't get something for nothing, especially in image processing.


Siggy is copyright 2006 Sean M Puckett, all rights reserved. Siggy may not be distributed except via direct download from its homepage at


All content on is the property and responsibility of the contributor. Don't steal. Use your head.