tims@teklds.TEK.COM (Tim Stoehr) (11/17/88)
I'm having a problem with my first use of the 'image' operator.
The postscript program below, according to my postcript book, should generate
the following 20 by 20 bitmap, scaled to one inch by one inch.
11111111111111111111:fffff
11111111111111111111:fffff
11111111111111111111:fffff
11111111111111111111:fffff 72 72 scale
11111011111111111111:fbfff 20 20 1 [20 0 0 20 0 0] {<fffff fffff fffff fffff
11111011111111111111:fbfff fffff f800f fbfff fbfff fbfff fbfff f81ff fbfff
11111011111111111111:fbfff fbfff fbfff fbfff fbfff fffff fffff fffff fffff>}
11111011111111111111:fbfff image
11111011111111111111:fbfff showpage
11111000000111111111:f81ff
11111011111111111111:fbfff
11111011111111111111:fbfff
11111011111111111111:fbfff
11111011111111111111:fbfff
11111000000000001111:f800f
11111111111111111111:fffff
11111111111111111111:fffff
11111111111111111111:fffff
11111111111111111111:fffff
11111111111111111111:fffff
I expected a black upside-down 'F' to be generated, instead I got random
garbage. Any distribution of blanks in the hex string made no difference.
What am I doing wrong?naughton%wind@Sun.COM (Patrick Naughton) (11/17/88)
In article <4181@teklds.TEK.COM> tims@teklds.TEK.COM (Tim Stoehr) writes: >I'm having a problem with my first use of the 'image' operator. >72 72 scale >20 20 1 [20 0 0 20 0 0] {<fffff fffff fffff fffff >fffff f800f fbfff fbfff fbfff fbfff f81ff fbfff >fbfff fbfff fbfff fbfff fffff fffff fffff fffff>} >image >showpage > >I expected a black upside-down 'F' to be generated, instead I got random >garbage. Any distribution of blanks in the hex string made no difference. >What am I doing wrong? You are describing your string incorrectly. Read page 24 of the Red Book. "A string may be described in hex... by bracketing a sequence of hex characters... Each pair of hex digits defines one character of the string. ... Spaces, tabs, and newlines are ignored." if you want some bits in the upper nibble (left half for depth 1) of a byte you need to specify the lower nibble as zero. Your example: f81ff fbfff translates to: f8 1f ff bf ff not as expected: f8 1f f0 fb ff f0 Here's your upside down F: %! 72 72 scale 20 20 1 [20 0 0 20 0 0] { <fffff0 fffff0 fffff0 fffff0 fffff0 f800f0 fbfff0 fbfff0 fbfff0 fbfff0 f81ff0 fbfff0 fbfff0 fbfff0 fbfff0 fbfff0 fffff0 fffff0 fffff0 fffff0> } image showpage -Patrick ______________________________________________________________________ Patrick J. Naughton ARPA: naughton@Sun.COM Window Systems Group UUCP: ...!sun!naughton Sun Microsystems, Inc. AT&T: (415) 336 - 1080
blm@cxsea.UUCP (Brian Matthews) (11/19/88)
Tim Stoehr (tims@teklds.TEK.COM) writes: |I'm having a problem with my first use of the 'image' operator. |20 20 1 [20 0 0 20 0 0] { [data] } image RTFM. From page 74 of the Postcript Language Reference Manual (the red book): "If bits/sample is less than 8 and width is not a multiple of the number of samples per character, there must be extra samples at the end of each row to fill up the last character. The values of the extra samples are not used; they are present only in order to align the data so that each row starts on a character boundary." In your case, bit/samples (1) is less than 8, and the width (20) isn't a multiple of the number of samples per character (8 / 1 = 8). Pad each line to 24 bits. -- Brian L. Matthews blm@cxsea.UUCP ...{mnetor,uw-beaver!ssc-vax}!cxsea!blm +1 206 251 6811 Computer X Inc. - a division of Motorola New Enterprises