|
Post by Marsrocks on Jan 11, 2012 11:23:19 GMT -5
secure.wikimedia.org/wikipedia/en/wiki/GrayscaleIn computing, although the grayscale can be computed through rational numbers, image pixels are stored in binary, quantized form. Some early grayscale monitors can only show up to sixteen (4-bit) different shades, but today grayscale images (as photographs) intended for visual display (both on screen and printed) are commonly stored with 8 bits per sampled pixel, which allows 256 different intensities (i.e., shades of gray) to be recorded, typically on a non-linear scale. The precision provided by this format is barely sufficient to avoid visible banding artifacts, but very convenient for programming due to the fact that a single pixel then occupies a single byte. Technical uses (e.g. in medical imaging or remote sensing applications) often require more levels, to make full use of the sensor accuracy (typically 10 or 12 bits per sample) and to guard against roundoff errors in computations. Sixteen bits per sample (65,536 levels) is a convenient choice for such uses, as computers manage 16-bit words efficiently. The TIFF and the PNG (among other) image file formats supports 16-bit grayscale natively, although browsers and many imaging programs tend to ignore the low order 8 bits of each pixel. No matter what pixel depth is used, the binary representations assume that 0 is black and the maximum value (255 at 8 bpp, 65,535 at 16 bpp, etc.) is white, if not otherwise noted.
|
|
|
Post by thewatcher on May 19, 2013 8:34:25 GMT -5
Just to add to this important thread Mars: Grayscale is the default state of all image from ground based rovers. Color is added later from filtration settings, light temp readings etc. The color calibration disk (though a faulty) was to aid in color calibration later. Color is a subjective nightmare. the brain generates this. Gray scale is a more reliable base for structure. A very important Post Mars. Unfortunately this will whistle passed many an anomaly hunters ears.
GJ A+
|
|