Monday, September 3, 2012

How to Make a White Balance Adjustment to your Photos

I commented on a previous hike (and several other times) about adjusting the white balance of your images to get more pleasing results . . . especially of the skin tones.  Our eyes are remarkably flexible and nimble in interpreting lighting conditions to render what we see.  But cameras do not easily adjust necessarily the way we perceive things.  A picture taken in a room lit by an incandescent light bulb comes out with overly warm orange-casts while the same image under fluorescent  lighting may appear overly green.

Sometimes we want these effects . . . as in pictures taken during sunset for the vibrant red colors produced by ambient light that has taken the long way through the atmosphere and color-shifted down into the reds.  My favorite time to take pictures is in the late afternoon when the light from the sun is actually warmer (color-wise).

Getting out into the forests adds a slight wrinkle to photography . . . while the light from the sun may be good, it is reflecting endlessly back and forth off of a lot of green vegetation and leaves and that light is adding a slight green tinge to your photographs.  The same sort of thing would happen if you took a picture in the deep earthen tones of the badlands of Eastern Washington and wondered why everything took on a very 'tanned' look. What is needed is a way to shift the overall color-balance of the image back to "standard" sunlight . . . remove that greenish, or reddish or whatever tinge.  Adjusting the white balance during post-production is one easy way to take a major step in restoring what your eyes have seen.  I'm going to show you how to do that in two popular and free image editing programs . . . PhotoScape and G.I.M.P.

Both these programs are free and contain no annoying spyware.  PhotoScape is the easier to use while G.I.M.P. is a very powerful, almost clone of Adobe's expensive Photoshop.  Both will allow you to adjust the white balance of an image.

A Note on Image Editing:

The de'facto format for storing an image nowadays is the Jpeg format (the .JPG extension on your pictures).  JPeg is a lossy format, meaning that information is lost every time you edit and resave the image.  After a number of edits and saves a Jpeg image will begin to take on artifacts that degrade the image.  It usually takes quite a while for these artifacts to become noticeable so you want to make ALL your edits at one time before you save the finished image . . . or save the interim image in a non-lossy format such as BMP or TIFF.  Needless to say, use SAVE AS with a different file name rather than SAVE so that you always have the original image to start over with.  PhotoScape makes this easy as it saves the originals into another folder automatically for you.

A Reference to Something White

The camera doesn't know what is pink or green or blue or white.  It only knows about the color temperature of the light reflecting off of objects in your image . . . even if that reflected light has had a lot of green added from bouncing around in the forest canopy.  But if we have something showing in our images that we know the color, we can use that as a reference to simultaneously correct all the other colors throughout the image later.  White is the best choice since white is a combination of all colors and the easiest to use as a reference.

The white reference I most often use are my white socks (since I'm a nudist and rarely wear much of anything else).  It could be a white hat or something as simple as a white piece of paper or an index card placed somewhere in the image where it can be cropped out later.  In the images used as examples below I used a pair of white socks carried in my fanny pack as a white reference.

Adjusting White Balance in PhotoScape

From the publisher of PhotoScape:

PhotoScape is an all-in-one style photo editor with fun and ease of use. Major capabilities are: viewer, editor, batch editor, page, combine, animated GIF, print, splitter, screen capture, color picker, rename, raw converter, resizing, brightness/color/white-balance adjustment, backlight correction, frames, balloons, text, drawing pictures, cropping, filters, red eye removal and blooming
PhotoScape is free and can be downloaded here.

Before adjustment
Adjusting the white balance of an image is simple within PhotoScape.  Click the drop-down arrow by 'Bright,Color' and select 'White Balance'.  Note that there is also a shortcut key combo to accomplish the same thing . . . 'CTL-W'.  A dialog box comes up with instructions.  The box can be dragged out of the way if necessary.

After Adjustment
Find something white in the image and hover the cross-hair cursor over it.  Click to see the changes the program will make.  If unsatisfied you can click in a slightly different area.  When satisfied, click 'Yes'.  Make any other adjustments you may want and then save the image.  Make sure you select the 'Make backup copy ...' during the save dialog.

Adjusting White Balance in G.I.M.P.

GIMP is an acronym for GNU Image Manipulation Program. It is a freely distributed program for such tasks as photo retouching, image composition and image authoring.
It has many capabilities. It can be used as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, an image format converter, etc.
GIMP is expandable and extensible. It is designed to be augmented with plug-ins and extensions to do just about anything. The advanced scripting interface allows everything from the simplest task to the most complex image manipulation procedures to be easily scripted.

GIMP has been described as the open-source version of Adobe's Photoshop, and like Photoshop, there is a steep learning curve to getting the most out of GIMP.   GIMP is sometimes slow and quirky in Windows (mainly because it was developed for the open-source community comprised mainly of Linux users and there have been a lack of dedicated Windows developers for GIMP).  However, the power of GIMP far surpasses the minor glitches that sometimes pop up.  GIMP can be downloaded here.

Before Adjustment
Within G.I.M.P. with your image opened,  select 'Colors' and then 'Levels' to open the Levels dialog.  This dialog can be a little intimidating but we are only interested in three buttons with eyedroppers near the bottom  . . . Black Reference, Grey Reference, and White Reference (Hint: Hover the cursor over each button for Tool Tips description).  Since white is the most common reference available in an image, click the outermost button,  Make sure the 'Preview' checkbox is selected.

After Adjustment
Moving the cursor over the image will change the cursor to a color-picker eyedropper.  As with PhotoScape, click in a known white area to preview the changes.  It not satisfactory, click a different area.

 G.I.M.P. saves in it's own proprietary lossless format, which is fine if you want to make changes in the future.  To save to the more common JPEG format you choose to 'Export' the image under the 'File' menu.

G.I.M.P. also has a handy facility to aid in post-production composition of your images . . . Guides:

Golden Means Gridlines overlain on the image.
Note how the axis of the torso is directly on one of the grids?
I've alluded to Golden Sections and composition before.  This handy facility aids you in cropping your images so that your subjects are situated in the most pleasing compositional arrangement.  Whenever you select or use the crop tool (it looks like a scalpel in the toolset), you have the option to overlay a grid over the selected area of the image.  Select a grid (or guide) from the dropdown box to the bottom right.  The goal is to crop (or move) your image so that the subject falls on one of the intersection points of the lines . . . or on the line, itself.

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