Adobe Illustrator - Re: Vertical and horizontal lines antialiased at export (and i don't want them to be!)

Author

Re: Vertical and horizontal lines antialiased at export (and i don't want them to be!)

jbl

2006-06-08, 6:18 pm

On Thu, 08 Jun 2006 14:48:31 +0200, Philours
<Philours@-NoSpam-philours.com> wrote:

>Hello !
>I've made a vector template into illustrator (CS2) and want to export it
>into photoshop (CS2 too) for web purpose.
>I noticed that each time i export a vector into a bitmap with
>antialiased turned on it smooth *all* of the document, wich would be
>fine and ok in theory except it also smooths the pure vertical and
>horizontal lines (which do not require any type of antialiasing as they
>are purely straight).
>I've tried exporting the document with and without background, and into
>various type of formats (PSD, BMP, EPS, PDF, etc.) and tried also to
>directly import the .AI into photoshop (worst result).
>Is there something i missed into the export preferences or something
>i've done wrong ?
>I precise that the document setup size into illustrator (the artboard
>size in pixels) matches the final result i aimed at into photoshop (and
>the color space is the same ie:RGB).
>Of course i need to export it with antialiased turned on because of non
>straight elements into the template...
>Thanks in advance for your help.
>Philours.

There is no way to export or save vector objects from illustrator to
photoshop without them being rasterized. Even purely "straight" lines.

It is a simple matter to "clean up" the straight horizontal and
vertical lines with the photoshop pencil tool.
jbl

Doug Winger

2006-06-08, 6:18 pm

In article <4488414c$0$19186$626a54ce@news.free.fr>,
Philours <Philours@-NoSpam-philours.com> wrote:

> jbl a écrit :
> Yes that's what i've done by the end but i still think that
> rasterization would not have to antialiased purely straight lines (don(t
> you ? :) ).
> Anyway, thanks for the help. :)

Your trouble arises from the antialiasing algorithm having to deal with
fractional pixels. If you're using, I assume, the 'standard' 72 dpi for
display screen resolution, unless the bezier line lies exactly along the
center of a pixel, the algorithm will spread the joy to the next cell.

The partial cure is to make sure that there's no fractional measures in
the line's location, and that end resolution matches line weights, e.g.
making sure that box's lines locations 'line up' along whole numbers
with no fractional component (unless the line weight requires it) and
the line weights translate directly into a pixel.

The above is one of the reasons that many people use 72 DPI when
figuring on screen display. Illustrator's point measure translates
directly into pixels. It makes 'lining up' lines with pixels during
later translation a lot easier.

- Doug

Doug Winger

2006-06-08, 6:18 pm

In article <448852ca$0$6978$636a55ce@news.free.fr>,
Philours <Philours@-NoSpam-philours.com> wrote:

> Doug Winger a écrit :
[color=darkred]
> Nice point Doug, it's absolutely relevant in this case. I noticed that
> the vector shapes in photoshop do the same as they are not aligned
> precisely.
> Do you mean i have to use the grid with pixels in unit and aligne each
> of my lines to grid separation ? I assume it would solve the problem in
> this case right ?

Partly. The key to this is making the line edges match a pixel's 'edge'.
For instance, when using a one point line in Illustrator with 72 DPI
your final destination, you have to make sure that the line itself
'splits' the pixel: that it centers on a 0.5 point dimension so that the
'edges' of the line lie on the desired pixel edges after conversion,
while a two point line needs to line up 'on the grid' so that its edges
fill the two pixels it traverses. Odd number size strokes can be a
headache, as they just don't 'fit' properly or easily. Thankfully,
simple filled objects just have to line up on whole number dimensions
and are easier to lay down.

It's primarily thinking ahead, setting up for end resolution, some
simple math, trying to work at final size and always keeping in mind
that you have to treat strokes as if they were actually rectangles
(which they are, to postscript :). Using guidelines, a grid (with nudge
set to provide any necessary fractional moves), move and the Transform
make things a lot easier.

- Doug