thinking outside the box Photo Editing Basics, Part 3  Brightness Levels and Color Balance XARA TUTORIAL
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This image below is dark and the histogram reflects that. It doesn't mean it's under-exposed, just that the image contains a lot of dark areas. It still has a good distribution of brightness levels because you can see that there are shades covering the whole range, albeit very slight on the light end. The white balance is perhaps questionable - it's a very orange image - but that's because they are gold painted Buddhas in a dark temple, lit with incandescent lights and candles.   There's not much that can be done to improve this image. However, I have adjusted the white point down to 236, and also given it some slight brightening of the low to mid shades by dragging the gamma to 1.14. Finally, I have adjusted the white balance by dragging the grey 'eye dropper' icon from the histogram dialog over a grey part of the image (the room background). You can see this has improved the detail and colors of the garments. White balance White balance is the process of getting the colors in your images as accurate as possible. All cameras have some basic white balance settings such as Auto, Tungsten, Fluorescent, Daylight/Sunny, Cloudy and Flash, but many amateur photographers do not use them or, quite commonly, forget to change them back when moving from one scene to another, resulting in images that are too yellow, orange or blue. The levels dialog allows you to adjust the overall color balance, in particular, the white balance so you can improve the photos that have been taken with the wrong settings on your camera.   The white balance for this image was incorrectly set for interior incandescent light as it was not reset to daylight when returning outside - the result is a strong blue cast to the whole image. The histogram show a good range of shades, but lacking at both ends, with not many really dark or really light shades, which corresponds to a lack of contrast.   I've moved the black and white points to the ends of the histogram to re-distribute the shades. The largest change is achieved from adjusting the white balance by dragging the grey 'eye dropper' onto a grey object (I used the man's hair). As you drag the dropper over your picture you can see it changing, sometimes dramatically, as it looks at the pixels under the mouse pointer and tries to adjust the balance of the whole picture so that the pixels under the pointer are grey. You can see that the garment and face colors are slightly better, but it's probably impossible to get a perfect color balance when the photo is so wrong in the first place. I've also cropped it to try and improve the composition and I've sharpened it. The resultant image is a significant improvement, even if it's far from perfect. The Curves Control Some software has a separate 'Brightness Curves' dialog that also lets you adjust the brightness levels. Xara combines this 'curve' control into the same dialog - it's the green line you can see drawn across the histogram. This green line represents a mapping of input shades to output shades.  So a straight line, from bottom left to top right, means that there's a 1:1 mapping. In other words, blacks convert to black and whites to white, and a brightness level of 128 is 128 ie. no change.  As you adjust the brightness slider on the InfoBar (or the middle grey small triangle under the histogram, which does the same thing) you will see that the green line bulges. (You can see this in the above screen shot). What this means is that the darker shades are being lifted slightly. If you adjust the contrast or the black or white points you can see the green curve change to reflect the new mapping curve. But it goes further than just showing the curve as a green line - you can drag on the curve to create any brightness mapping curve you like. This is an immensely powerful way of adjusting the brightness levels of pictures.  As a simple example here's one where I have dragged on the curve in two places to create a new mapping curve (the pale blue line).   You don't need to see the picture to understand what this does. By lifting the dark end, and dropping the bright end, I have in effect reduced the contrast of the image and you can see this reflected in the histogram. Actually, there was nothing wrong with the original brightness levels - they were well centered and with a good distribution, but you can see the new histogram (the pale overlay) results in less contrast - that is fewer dark and fewer light shades. In this second histogram, I've done the opposite - moved the dark end down (made the darker shades darker), and moved the lighter end of the curve up.   The new histogram is now more spread over the brightness range giving brighter whites and darker blacks, in other words a high contrast image. You can see this degree of manual control allows you to adjust any part of the brightness range without affecting other parts. So you could, for instance, darken really bright parts of the picture, but leave all dark and mid-tones as they are. I've only touched on some of the capabilities of the Histogram Levels and Curves tool, but it's worth mastering as it’s a very powerful, fast and interactive way to adjust image brightness, contrast and white balance levels, all in one dialog. For more information on the photo tool in Photo & Graphic Designer and Designer Pro see the two earlier tutorials in this photo editing series: Photo Editing Basics, Part 1 - an intro to the terminology, formats & sizing Photo Editing Basics, Part 2 - an overview of all the photo tools Xara's unique non-destructive nature maintains the high quality of your original photo regardless of how many times you open-edit-save it. As a result many people use Xara Photo or Graphic Designer 2013 as their primary, general purpose image and document composition tool. Check out our Resource index, which offers a searchable and browsable list of movies and tutorials created by Xara and third parties.
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