Are the whites hot?

[Kerry Perkins]

One of the most difficult aspects of an image to evaluate (especially with birds it seems!) is the level of the peak whites. Are they blown? Are they not blown but still too hot? There is a lot of discussion about this topic and it is often stated that the viewer's monitor may be contributing to the evaluation. While it is true that monitors often vary (especially if not calibrated frequently), but there is an easy, definitive way to determine the absolute value of any pixel in your image.

There are free applications for both Windows and Mac that let you see exactly what values are being displayed on the monitor, and since they are reporting what is in the file, the monitor becomes a non-issue. You can use this method on a monitor that is horribly mis-adjusted and still be assured that the peak values are what you think they are.

Here is a screen shot of one of my images. You can see that I have the "DigitalColor Meter" (a utility that comes with every Mac - it's in the Utilities folder) open on top of the image. The way the color meter works is that you simply place your cursor over the image and it tells you the 8-bit values that each pixel contains. You can't see the cursor in this screen capture because the capture program doesn't include the cursor (you wouldn't want it to normally), but you can see in the detail window of the meter that I am looking at some pixels that are just to the left of the eye. By looking at these values I can tell that my "whites" are not even close to being clipped (255-255-255) and are within the comfort range. Ideally, I don't like to have any color channel go over 245, and you can see that blue is at 247 but it seems to work ok in this image.

For Windows users there is a nifty free program called "ColorPic". You can download it here - http://www.iconico.com/colorpic/ . I find this little gem to be much better than the free Mac one but it works the same way. (I use Parallels on my Mac to run Windows XP, and I have tested this application.)

Using one of these utilities will take the guesswork and opinion completely out of the equation when evaluating white levels. Since you are looking at what is in the file, the display device has no bearing on the evaluation and you can see exactly what is posted on web sites. As you can see in my example, I am looking at my image on the BPN site and I can be confident that the whites are exactly what I wanted them to be all the way to the end of the process.

This technique is also useful for evaluating color casts. All shades of gray, black, and white are, by definition, combinations of the three primary colors in equal amounts. Colors are always specified as "red-green-blue". Absolute black is 0-0-0 and absolute white is 255-255-255 in an 8-bit image, which is what we post on the web. Neither of these values should be present in your images (a general rule of course), as they indicate a complete lack of detail in those areas. If you are looking at plumage that is supposed to be gray, you should see a reading like 128-128-128 (50% gray) or something similar based on the light level. If you see 128-128-135, you are looking at a bluish cast. This can be very useful and also take monitor calibration right out of the picture, so to speak. It is also an excellent way to verify that you don't have a color shift between your workflow and your web images.

I hope you find this helpful!