Hi Marcos, The SAM palette is make up using 2-bit RGB plus intensity, which bitwise is: xGRBigrb. For pure greys you'd use:
00000000 = 00 = 0 00000111 = 07 = 7 00001000 = 08 = 8 00001111 = 0f = 15 01110000 = 70 = 112 01110111 = 77 = 119 01111000 = 78 = 120 01111111 = 7f = 127 The SAM demo tape astronaut image uses cyan to fill some of the gaps, which duplicates black and white on the ends: 0, 0, 8, 5, 7, 13, 15, 82, 112, 90, 120, 117, 119, 125, 127, 127 That's maybe as good as you'll get for a 16-colour palette. Si On 19/12/2012 20:43, Marcos Cruz wrote: > Hi all, > > In order to automate and simplify as much as possible the process of > importing images into the SAM and avoid the palette conversion problems, > I'm tinkering with the Netpbm raster formats > (<http://en.wikipedia.org/wiki/Netpbm_format>). BMP and others could be > used too, but Netpbm files have two encoding variants (ASCII and binary) > for every type (PBM, PGM and PPM), what makes them very versatile in > this case. > > The Netpbm images are created with Linux tools and the SAM does the > final conversion, PLOTing the image pixels with the desired equivalent > colors and GRABbing it. > > The first tries with a grayscale image look promising, but I need to > choose 16 grays from the SAM palette (0, 7, 8, 15, 112, 120, 127...?) > I'm afraid there are less than 16 gray tones, and blue must be used to > complete the set. Am I right? Does anyboy know which are the best 16 SAM > original colors for a grayscale? > > Thank you. > > Marcos > >
