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> Hi Steve, > > I'm having a question on precipitation values from the generated GIF file by > nex2img. We have three different RADMOD (C/P/M), and from Gempak display, > the max(in inches) is sometimes 8 or 4 on each site, although the color > levels are always 16. > > If I read a pixel as PaleGreen3 from n1p.gif, how can I determine the number > of inches for this particular location? > > I checked nex2gini.tbl and you specified as below: > N1P 30 3 inches,10,110,0,2;110,210,2,6;210,255,6,12 TICZ99 CHIZ > > Could you explain this a little bit? > thanks a lot! > > Ying Cao Ying Cao, The level 3 data products are 16 bins as you notices, and the nex2img program will determine the data range that those represent when compositing into the image. The nex2gini.tbl file provides a series of ranges for pixel and data values. For the N1P product, the "30" is a product number for identification in $GEMTBL/sat/imgtyp.tbl. The next number "3" is ths number pixel to value sets. The final grouping: inches,10,110,0,2;110,210,2,6;210,255,6,12 Provides the units, followed by the "3" pixel to value sets. Here, it says that pixel values 10 to 110 represent the data range of 0 to 2 inches. Pixel values of 110 to 210 give the range 2 to 6 inches, and the pixels 210 to 255 give the range 6 to 12 inches. The purpose of having 3 range sets is to allow greater resolution (eg 100 pixel values for the 0 to 2 inch range) at the lowest end. Similarly, the level 3 radar products do not provide a linear set of bin/values but instead concentrate the number of bins in the area of needed resolution. For a program plotting a gini from the nex2gini output, the IMCBAR would provide a color bar refernce of data value to pixel value. The nex2img program was designed to provide just the image. You can reference the implied data value of a pale green pixel though its gif value and then calculate the value within the data range in nex2gini.tbl that pixel represents. Steve Chiswell Unidata User SUpport > > Ticket Details =================== Ticket ID: AHI-786143 Department: Support GEMPAK Priority: Normal Status: Closed