Asked in Units of MeasureAcronyms & AbbreviationsVolume
What is parts per million PPM?
May 06, 2017 6:50AM
1g NaCl/1000g H20 (1,000,000)
0.001 x 1,000,000
1000 ppm is your answer.
In other words, ppm measures the concentration of a chemical in very low quantity. For example, seawater has 0.5 ppm of pure gold, while human blood contains 20 ppm of iron oxide. This unit is used when other units like % and fractions are too big to denote the quantity. Since a percent is one part in a hundred, you can image how small ppm is compared to %.
8 milligrams of mercury in 100 grams of fish would result in a mercury concentration of 0.8 ppm.
Where width, height, and maxval are in ASCII decimal for the width, height, and maximum sample value of the image, respectively. The header portion can also include human-readable comments by using the # character followed by a comment. The image data is just a bunch of uncompressed bytes containing the red, green, and blue sample values of each pixel. There are similar formats called Portable Greymap (PGM) and Portable Bitmap (PBM), and they are defined and treated similarly.
There are many tools for transforming and converting files of these types to other formats. Search for Netpbm for more information.