From: brox@corena.no (Bjorn P. Brox)
Subject: pbmplus10dec91, xwdtopnm : white isn't white anymore..
Date: Sat, 29 Aug 1992 13:32:36 GMT
Organization: CORENA A/S


I posted this directly to Jef Poskanzer for about 3 months ago, with no
responce. This is just to make shure that it is fixed in the next version
of the pbmplus package:

I have some problems with xwdtopnm.
Using xmag on the screen shows that white is (0xff00, 0xff00, 0xff00)

When I dump a window using "xwd | xwdtopnm >file.pnm" the white color
becomes (0xfe, 0xfe, 0xfe) (sometimes 0xfd..), which looks white, but isn't
white enough... (A PostScript B&W printer gives you a thin shade, you will
also sometimes get some effects using xwdtopnm|ppmtopgm|pgmtopbm.

The error shows up when when converting from short to char on the color
table, like in the statement at line 367, where *maxvalP = 255:
	x11colors[i].red =
	    (long) x11colors[i].red * (long) *maxvalP / 65535L;
Shows that:
	0xff00*255/65535 = 254

I am using an IBM RS6000/320, AIX 3.2, X11R4.

senja:brox> xwdtopnm -version
xwdtopnm: Version of 10dec91
xwdtopnm: BSD defined
xwdtopnm: PBMPLUS_RAWBITS defined
xwdtopnm: RGB_DB="/usr/lib/X11/rgb"
xwdtopnm: LIBTIFF defined
senja:brox> 

Below is a small uuencoded compressed xwd file you can test xwdtopnm on.

begin 664 mailbox.xwd.Z
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M`"@`WY;J!&#@!X`K`!@Q#7C`!`"-5+8"0!`&P"$`V<0FP`0`&`!H8A6X`N`,
MP#NQ"\````0`DE@&?``0`L!V:@./4QTXK"+V@<-58B$X+$HP0D#&7!U*N`R`
M\=0)G"%/I<"9<L`*`2%G)F@A=6>Q%UR+=HC!M6D`&0+:7!U0@^[74S?\GDV0
MP^_;'3`3G.I!N6>''Y03KZC\=@C&RJ>*P`[<X0CNTP&0X'Z[!&/58DV<[T[P
MQ/KP*-;?3L%XMU@5]=D'7)$_/(O\M[6`'F\`N(#><P2]@%YX,*!W6PR09>>0
M#!'J!\`,%89'0X6WU0`9>E/9\*&%-XP8'@XCWI8#9/9-I0.+%NX`8W@\P'A;
M#_81Z(-]"`;T@WWA`6'?;4'8)"%!0AAIX1!*AD>$DK<581.(#ADQI85'7!D>
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MQ;VRD>G<XBD+.,!WOK&:X7MG--^8P(1FL6MK6V@PR_C1CU:RD`^=Y$2O^-*8
"5@FR
`
end

-- 
Bjorn Brox, CORENA A/S, Baneveien 38, N-3600 Kongsberg, NORWAY
E-mail : brox@corena.no, Phone : +47 3 73 66 11, Fax : +47 3 73 68 77