Consider the example below, where the original color image makes the red parrot stand out against the near colorless background. Move your mouse over the options below to view some of the possibilities. Of course, images rarely contain just one color. Black and white conversion may therefore require interpretive decisions.

Notice the contrast changes both between and within regions of red, green and blue above. Pure red or primarily red color filters often work best for landscapes, as this increases texture in regions containing water, sky and foliage.

Each image may therefore require its own combination of red, green and blue filtering in order to achieve the desired amount of contrast and tonal range. Whether you specify it or not, all conversion techniques have to use some weighted combination of each color channel to produce a grayscale brightness.

Some techniques assume a combination for you, although the more powerful ones give you full control. It is undoubtedly one of the most powerful black and white conversion methods, however it may take some time to master since there are many parameters which require simultaneous adjustment. Channel Mixer in adobe photoshop. Below and to the left would have been the planet Saturn. The amount of data in an image has much more to do with the resolution of the image than its color property. The Mars probes do take black and white pictures, but they are taken through color filters.

For instance, Phoenix has a set of 8 colored filters. By analyzing how much light gets through each color of filter, we can make good guesses as to the composition of what were looking at. You just couldnt do that with a normal color camera. As such they tend to take a lot of storage space. PNG will be free from loss of detail. However, regardless of file format, nothing stored on digital media should get corrupted over time, unless the media itself degrades or is damaged.

No file format is any more or less subject to this, what you store is what you store, period, be it image, sound, text, or anything else. Another thing that degrades quality is changing image size. So check the file dates on your JPEG images, to see if they have been unexpectedly updated. Because as I said, theres nothing inherent to the JPEG format that predisposes it to corruption over time.