stroke and fill

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15 total messages Started by David_Cristian Tue, 22 Jul 2008 15:11

#319

Author: David_Cristian
Date: Tue, 22 Jul 2008 15:11

17 lines
1291 bytes

I read in the PostScript documentation and i saw that stroke only has :
-linecap
-color
-mitterlimit
-linejoin
-thickness

I have to write an application and my class
Stroke, that i am using, has a lot of other stuff like PatternBrush, ImageBrush ,GradientBrush , etc.

Can i get this kind of options for stroke in a PostScript file?
How about Fill?
(I'm very interested in the gradient option. I haven't found so far very clear documentation about it)

Can i get a detailed explanation or(and) some reference?

David

Re: stroke and fill

#320

Author: Aandi_Inston
Date: Tue, 22 Jul 2008 16:01

6 lines
1011 bytes

You can use a tiling pattern to produce an implementation of a brush.
A pattern is, in effect, a color, so after using setcolorspace and
setcolor to set a pattern color, fill, eofill, stroke, imagemask and
the text operators will all paint with your brush.

Aandi Inston

Re: stroke and fill

#323

Author: David_Cristian
Date: Wed, 23 Jul 2008 08:01

3 lines
841 bytes

Can you give me an answer about the second question (matrix transformation)?

David

Re: stroke and fill

#324

Author: Aandi_Inston
Date: Wed, 23 Jul 2008 08:27

3 lines
729 bytes

"concat".

Aandi Inston

Re: stroke and fill

#325

Author: Aandi_Inston
Date: Wed, 23 Jul 2008 08:28

5 lines
1002 bytes

By the way, the PostScript Reference is the complete definition of
shadings. Does anything seem to be missing (rather than awesomely
complicated?)

Aandi Inston

Re: stroke and fill

#326

Author: David_Cristian
Date: Wed, 23 Jul 2008 10:48

4 lines
701 bytes

It is a lot to read and I lost myself a little bit.
I'm sorry if I ask too silly questions .

David

Re: stroke and fill

#327

Author: David_Cristian
Date: Thu, 24 Jul 2008 08:46

16 lines
867 bytes

I have another question.

I tried to draw a line with the following color:

200 143 120 setrgbcolor

and it doesn't seem to work

if i change only that line like:

255 0 0 setrgbcolor

it draws a red line.
What am I doing wrong?

David

Re: stroke and fill

#328

Author: Aandi_Inston
Date: Thu, 24 Jul 2008 09:59

11 lines
1188 bytes

You are not using the correct ranges for the color values. You are
assuming that they lie in the range 0 to 255, but that is not the
case.  See "DeviceRGB color space" in 4.8.2. Each color space may have
different colorant ranges.

You may have seen 0..255 in RGB PostScript images, but this is just a
representation to be scaled to the true value using the (supplied or
default) Decode values. It would be 0..15 in a 4-bits-per-component
image, to represent the same range of values.

Aandi Inston

Re: stroke and fill

#329

Author: David_Cristian
Date: Thu, 24 Jul 2008 10:18

4 lines
846 bytes

I got it.
And another thing, if i am using a hexadecimal representation for images, does bits per component gives the info about how many colors it can use to draw it I am interested to 3 and 4.

David

Re: stroke and fill

#330

Author: Aandi_Inston
Date: Thu, 24 Jul 2008 10:24

12 lines
1190 bytes

BitsPerComponent indicates how many bits are used to store each
component and nothing else. But it does limit the number of separate
colours.

For example, with 4 bits per component, there are 16 possible values
to a component. An RGB image with 4 bits per component would therefore
have 16 x 16 x 16 possible distinct colours.

But I sense you are asking about something else, when you say you are
interested in "3 and 4". Can you give more details?

Aandi Inston

Re: stroke and fill

#331

Author: David_Cristian
Date: Thu, 24 Jul 2008 10:34

3 lines
689 bytes

My goal is to draw the images using RGB or CMYK for representing every component.

David

Re: stroke and fill

#332

Author: Aandi_Inston
Date: Thu, 24 Jul 2008 11:00

5 lines
947 bytes

>My goal is to draw the images using RGB or CMYK for representing every component.

Ok... but what is the question, related to bits per component?

Aandi Inston

Re: stroke and fill

#333

Author: David_Cristian
Date: Thu, 24 Jul 2008 11:14

5 lines
895 bytes

My question is actually the following:
How can I draw an image using 3 or 4 colors .
Actually this is my task and I don't really understand, after reading the documentation, what I have to do and I thought the answer was in the bits per component parameter.

David.

Re: stroke and fill

#334

Author: Aandi_Inston
Date: Thu, 24 Jul 2008 11:41

10 lines
982 bytes

You mean that the entire image will be made up of 3 colours, such as
RGB=10%,50%,0%
RGB=70%,14%,80%
RGB=80%,80%,80%
and there will be no other colours in the image?

If so, this is an ideal case for an Indexed colour space. You could
then use just 2 bits per component.

Aandi Inston

Re: stroke and fill

#335

Author: David_Cristian
Date: Thu, 24 Jul 2008 13:03

10 lines
1068 bytes

Let me get straight another thing.
When the postscript interpreter sees raw data and after that he sees
for example
(8 bits per component)
false 3 colorimage ...

He will analyze the data and associate a color to every 3 bytes(that means R G B i know 3 is for RGB)? Ex : ffff 0000 0000 => Red
With 4 => he will get a color at every 4 bytes (CMYK)?

So if I want to associate to every component a CMYK correspondent , i will have to make a conversion, ... no?

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