If you have a picture that is either too bright, too dark or too grey, then it is easy to change the picture. The process is simple.
We have this picture:
Whithout a doubt something must be done. I use the application GraphicConverter for Macintosh. But there are many other good applications for that purpose, e.g. GIMP (free of charge) and Photoshop.
The application must have the function Levels which creates this picture:
You drag the rightmost triangle leftwards against the right edge of the mountain. This right edge of the mountain corresponds with the brightest color in the picture which is pretty grey. The middle triangle is explained later.
There. This means that all the brightest gray colors shall be bright white. The next step is to drag the leftmost triangle rightwards to the left edge of the mountain:
There. This means that the darkest colors in the image shall be as dark as possible. If you want to change it further, maybe it is still too dark or too light, then try adjusting the middle triangle. This is called Gamma.
When using the function Levels, it is common in applications that you can see the picture changes as you make the changes with the mouse. Usually there is a button, which lets you choose whether you want to see the picture as it will look, or the picture as it was before. This button is called Preview in some applications. Click some times on this button in order to make an estimate whether an improvement has happened, or if the old picture should be kept.
When you are done, click OK or Cancel, depending on whether you are satisfied with the change or not. If you bring Leves up again it looks like this:
The mountain is stretched outwards. The picture becomes this:
Changed Sep. 7th 2006.