Author Topic: image resolution problem - jagged edges  (Read 5958 times)

mamboze

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image resolution problem - jagged edges
« on: April 08, 2012, 07:37:31 pm »
Hi,

I'm creating a brochure in Scribus and I've encountered a problem with a logo image. This image was made in GIMP, 100x50mm, 600dpi. When viewed in GiMP, it looks clean (no jagged edges) but when it is inserted into an image frame in Scribus, jagged edges are very apparent. The logo has curved sides which really accentuate the problem. The jaggies also show up when the brochure is exported as a pdf file and viewed in Adobe Reader.

The logo image frame size in Scribus is 50x25mm. I've had a look at some of the documentation in the Scribus Wiki but can't find anything directly relevant. 

Any help or comments would be much appreciated.

Wena

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Re: image resolution problem - jagged edges
« Reply #1 on: April 08, 2012, 08:00:25 pm »
I have often found that by opening the original in in Inkscap then save it as  a native file it then becomes a vector image which you can import into scribus, it dose not need a graphic box.

Wena.

mamboze

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Re: image resolution problem - jagged edges
« Reply #2 on: April 08, 2012, 08:40:53 pm »
@Wena I tried out your suggestion, the image was somewhat improved but really only marginally.

I think I'm setting the image parameters in GIMP correctly. I thought that if the image was larger than required in Scribus and with a fairly high resolution that should avoid any jagged edges. The png image when viewed in GiMP is fine, similarly for the Image Viewer, for both png and svg. Even with high levels of zoom, both images look good.

From my reading of the Scribus Wiki, png images are OK, preferable in fact. So, perhaps the problem lies with my settings in Scribus.

Thanks for your help


Mike

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Re: image resolution problem - jagged edges
« Reply #3 on: April 09, 2012, 12:05:56 am »
Something like this? (PDF: http://bugs.scribus.net/file_download.php?file_id=5476&type=bug)

If yes. It's because of transparency. You must create logo without that.

utnik

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Re: image resolution problem - jagged edges
« Reply #4 on: April 09, 2012, 12:24:27 am »
hi mamboze

the transparency problem could be the reason of your problem, but it's not the only possibility:
how are your image resolution settings when you export the pdf? if it's something around 150 ppi, your high resolution image will be downsized to a collection of pixel stairs. ask the printshop, what they require.
you don't need an image file with a higher resolution than what your printshop requires. the best would be to import a file which matches exactly this requirements – gimp is the specialized tool for pixel processing, not scribus…

utnik

mamboze

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Re: image resolution problem - jagged edges
« Reply #5 on: April 09, 2012, 05:35:28 am »
@Mike, yes so create logo without transparency, that is, with a white background?

@utnik, the logo image resolution is Actual-X-DPI and Y-DPI are both 1199.9.

I've had a look at http://wiki.scribus.net/canvas/Images_-_PPI_and_DPI

It suggests (at my reading) that the resolution of the image be matched to the size of the displayed image, so a required image width of 2 inches and a DPI of 300 would require a 600px width. But 'scale to frame size' option can be used too?

I'm sorry if I sound a bit confused about this stuff, I am. But I'm working thru the getting started pages so I hope to be up to speed soon

Thanks to you both

mamboze

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Re: image resolution problem - jagged edges
« Reply #6 on: April 09, 2012, 05:46:49 am »
@utnik  correction, on the basis of dpi = 2 x ppi (a rule of thumb?), the logo ppi is around 600.

mamboze

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Re: image resolution problem - jagged edges
« Reply #7 on: April 09, 2012, 06:26:09 am »
OK, I replaced the transparent background with the color I'm using in the brochure but when the image is inserted there is a rectangular border around the logo. I've checked the logo image in GIMP and there is no border there.

Apart from the border issue, going this way may be OK for uniform color backgrounds but using a gradient would make for problems. So I wonder is there another way to place a non-rectangular image in Scribus?

mamboze

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Re: image resolution problem - jagged edges
« Reply #8 on: April 09, 2012, 06:41:13 am »
Hi, I printed out the brochure and no border apparent. I suppose this is a typical newbie mistake. LOL.

Thanks guys for all your help. On with the getting started series  :)


Mike

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Re: image resolution problem - jagged edges
« Reply #9 on: April 09, 2012, 12:53:58 pm »
To mamboze: It's not necessary to create image with smaller size. Scribus will do it for you. Just check Maximum Image Resolution at the bottom part of Save as PDF dialog and set up 300 DPI (for print).

Gradient:
  • Create (in Inkscape or GIMP) big rectangle (with gradient) that fit the page (logo will be much smaller).
  • Try to use vector graphics (without blur and transparency).

Yes. Scribus can create image frames with non-rectangular shapes. You can look at Scribus Creations on page 5: http://www.scribus.cz/stahnout/dokumentace/ScribusCreations.pdf

mamboze

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Re: image resolution problem - jagged edges
« Reply #10 on: April 10, 2012, 03:22:33 pm »
@Mike
Of course, put the logo in a complete page. Thanks. And that would work for a image used as a background too. I haven't used Inkscape that much but I'm reasonably familiar with the bezier technology thru GIMP and PS.

BTW I couldn't download the ScribusCreations.pdf, the link seems to be broken.

http://documentation.scribus.net/index.php/Tips_and_Tricks  provides some info, but it might be an intensive process for the logo I'm wanting to use (see attached image)