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Author Topic: Enlarging images  (Read 2292 times)

Justinr

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Enlarging images
« on: October 30, 2015, 07:21:04 AM »

I have extracted a diagram from a PDF which I would like to use in an article (I have full permission to do so) but it needs to be of a much higher image quality before it can be printed. I have made some stabs at doing so in PS using the Image size function, both in TIFF and JPEG format, but no joy. All suggestions appreciated!

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Torbjörn Tapani

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Re: Enlarging images
« Reply #1 on: October 30, 2015, 07:29:59 AM »

I have extracted a diagram from a PDF which I would like to use in an article (I have full permission to do so) but it needs to be of a much higher image quality before it can be printed. I have made some stabs at doing so in PS using the Image size function, both in TIFF and JPEG format, but no joy. All suggestions appreciated!

So, it's a raster image no bigger than what we can see here? You could give Live Trace a go in Illustrator or http://vectormagic.com/
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BartvanderWolf

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Re: Enlarging images
« Reply #2 on: October 30, 2015, 08:24:02 AM »

I have extracted a diagram from a PDF which I would like to use in an article (I have full permission to do so) but it needs to be of a much higher image quality before it can be printed. I have made some stabs at doing so in PS using the Image size function, both in TIFF and JPEG format, but no joy. All suggestions appreciated!

Hi Justin,

Not much to go on, but PhotoZoom Pro makes a usable and improved enlargement. The best option, as mentioned, is to re-vectorize the raster image (but the source is pretty low quality to begin with).

Cheers,
Bart
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Justinr

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Re: Enlarging images
« Reply #3 on: October 30, 2015, 09:24:28 AM »

Thanks gents, I've had a shot at those and a couple of others that your suggestions led me to but at the end of the day you both hinted at the basic problem and that's the original image is too small to do anything sensible with. Vector Magic did best but it still lost the precision that I was hoping to keep.

Unfortunately the image was taken from a 1974 technical briefing by what is now the ABB Group (http://www.abb.com/) they were very good in sending the PDF and I got the impression that's all they had, which is remarkable in itself, so I might end up drawing my own diagram of how it works (it's a pressure wave supercharger).

The other thing that struck me was how useful micropayments would be useful in situations like this. Vector Magic was something like $300 or $8 a month which is fine, they are in business after all, but it's something I might only use once or twice a year. A dollar or two for an image or two would certainly suit folk like me.
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Torbjörn Tapani

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Re: Enlarging images
« Reply #4 on: October 31, 2015, 08:03:31 PM »

That got me thinking. There are services that manually remove backgrounds and create clipping masks, for one or many images. There must be a manual vectorization service. http://vectorizenow.com/ seems to be one of the first google hits.
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Zorki5

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Re: Enlarging images
« Reply #5 on: January 23, 2016, 07:31:18 PM »

Seems like I'm a bit late to this particular party, but'll chime in nonetheless -- in case someone needs this in the future.

The best option, as mentioned, is to re-vectorize the raster image (but the source is pretty low quality to begin with).

If the image in the PDF is a vector image (and the one in the OP does looks like that), then no, re-vectorization is not the best option, at all.

You don't need Adobe Acrobat to edit PDF files. There are great freeware solutions for that, the best of which is Inkscape (https://inkscape.org/en/). BTW, PDF files have almost the same format as Adobe Illustrator files, AI; it is even almost always possible to view an AI file while not having anything other than Adobe Acrobat Reader installed -- by simply renaming AI to PDF (that is, changing file extension from .ai to .pdf) and opening it. What I'm saying is that PDF is not some read/view-only format, you can mess with it quite a bit if you know how...

So, one way is to open that PDF in Inkscape, remove everything except that diagram, and save it as a PDF, AI, SVG or a ton of other vector formats that Inkscape supports.

If that fails, for whatever reason, then you can still at least render that particular page of the PDF, using Inkscape's command line tools, into some very high resolution bitmap and then use that.
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BartvanderWolf

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Re: Enlarging images
« Reply #6 on: January 23, 2016, 08:08:01 PM »

If the image in the PDF is a vector image (and the one in the OP does looks like that), then no, re-vectorization is not the best option, at all.

Hi,

But that's a big IF. It probably started life as a vector image, but for all we know the image now was just a low resolution JPEG embedded in the PDF.

Quote
You don't need Adobe Acrobat to edit PDF files. There are great freeware solutions for that, the best of which is Inkscape (https://inkscape.org/en/).

Yes, Inkscape is very powerful.

Quote
So, one way is to open that PDF in Inkscape, remove everything except that diagram, and save it as a PDF, AI, SVG or a ton of other vector formats that Inkscape supports.

And it also allows to re-vectorise raster image content. But given the low resolution, it would probably still need a lot of additional work.

Cheers,
Bart
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Zorki5

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Re: Enlarging images
« Reply #7 on: January 23, 2016, 08:38:30 PM »

But that's a big IF.

True. Probably, that (what kind of embedded image we're dealing with) should have been the first question to ask Justinr.

I only offered some additional info just in case; Justinr has asked his question in October 2015, so it was... a bit too late anyway.
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