Re: [Inkscape-devel] [Inkscape-user] Major Issue
Rick Spillane wrote:
On a related note, I'm trying to improve Inkscape's rendering quality a bit (nothing drastic, but the current about should look a bit better) and I've noticed that apparently Export to Bitmap doesn't use the exact same procedure as normal rendering (to screen). (I noticed because at one point I apparently broke something that didn't affect rendering to screen but caused export to bitmap to give a very obviously wrong output.) Could someone explain what's going on here?
On 7/11/06, Jasper van de Gronde <th.v.d.gronde@...528...> wrote:
Could someone explain what's going on here?
No, unless you provide a sample file and detailed explanations, best of all in the form of a bug report.
bulia byak wrote:
Well, I had hoped someone would simply say "yeah, sure, of course the export to bitmap function has a slightly different output, ...", but I guess that's not the case. But before actually filing a bug report I would like to have it confirmed that it actually is a bug, as I can think of reasons why export to bitmap might produce different outputs (I could imagine some sort of caching is used for on-screen display for example, which might change the order in which the different objects are composited). Anyway, have a look at the following two images:
http://home.hccnet.nl/th.v.d.gronde/gradient-test-new.png http://home.hccnet.nl/th.v.d.gronde/gradient-test-screenshot.png
They both come from the same version of Inkscape (the modified one I just posted about in another e-mail, but 0.44 has the exact same issue) and show the same file on the same scale, yet the banding and coloring are slightly different.
On Tue, Jul 11, 2006 at 07:29:13PM +0200, Jasper van de Gronde wrote:
Oh, I think I see what's going on. Inkscape has a defined "canvas area", as indicated by the document outline thingee. Anything overlapping or extending beyond that box is clipped when you export. In your screenshot it's clear you can see there is portions of the document extending beyond this boundary; it looks like inside the boundary everything is identical for both images.
Possibly you disagree with this approach, but it is only the default. Inkscape has some controls to let you disable/alter this behavior:
* In Document Preferences -> Page, adjust Show canvas border, show page shadow, etc. as suits you.
* In export bitmap, experiment with exporting page vs. drawing vs. selection vs. custom. This will allow you to export stuff that extends beyond the normal page boundary, or to clip it down to specific objects or specific dimensions of the drawing, or whatever you desire.
Hope this helps, thanks for posting the gfx. Bryce
Bryce Harrington wrote:
This is weird! When looking at the images with Firefox they indeed appear to be (virtually) identical (apart from the border of course, I just clipped a bit rough), but when I look at images with IrfanView (or Corel PhotoPaint, I didn't try any other programs) they seem to be different... (In fact, to make sure I wasn't going crazy I checked the histograms, after cropping properly naturally, the mean value is off by about 10.) Any gamma values or something similar being written to the PNG file?
I'm using a color profile for my monitor btw, but I don't think that should matter in this case (should affect both images in the same way when displaying them and shouldn't be affecting the RGB values reported for the image).
Jasper van de Gronde wrote:
To (hopefully) illustrate what I mean I've uploaded a screenshot of gradient-test-new shown from within IrfanView as well as Firefox (so to be absolutely clear, you're looking at the exact same image twice, one that was generated with export to bitmap):
http://home.hccnet.nl/th.v.d.gronde/gradient-test-screenshot2.png
On Tue, Jul 11, 2006 at 11:40:34PM +0200, Jasper van de Gronde wrote:
I've no idea what causes that. I would suggest posting this with a subject line more appropriate than just "Major Issue", and hope someone who understands the color stuff will answer. Otherwise, send in a bug report.
It's not clear to me whether the issue is actually with Inkscape, or with one of these other viewing programs.
Bryce
Jasper van de Gronde wrote:
Wait a second... it looks like there's transparency involved in the object the gradient is applied to and the canvas is most likely transparent as well... is this possibly the issue with the PNG export?
In Inkscape it will render on the white (transparent) background, but, the PNG would just have transparency w/o that "artificial" white. I guess the quick test is to make the background opaque in the document properties and test exporting to PNG again.
-Josh
participants (4)
-
Bryce Harrington -
bulia byak -
Jasper van de Gronde -
Joshua A. Andler