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Author Topic: resizing images  (Read 24111 times)

Gordon Buck

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resizing images
« Reply #40 on: February 17, 2006, 10:49:58 am »

Drew,

How/when do you sharpen the image when printing from Qimage?
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Gordon
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Ray

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resizing images
« Reply #41 on: February 17, 2006, 11:56:43 am »

Gordon,
Under the heading 'Prints' at top of page, go to 'print/Image interpolation". The options for final print sharpening are 'smart sharpening', 'normal sharpening' plus a slider that takes you from off, default, med to high.

What I find interesting about Qimage is the great choice of interpolation algorithms. I've been using the default 'Pyramid' algorithm which appears to be the best quality, but I've never bothered comparing any of them on actual prints. The list of options (with a 'quality' no. in parenthesis) is as follows:- Pyramid (10), Vector (8), Lanczos (7), Bicubic (6), Mitchell (5), Triangle (3), Hermite (3) and Bell (3).

Pyramid also has a slider that goes from smoother to sharper. Again, I've never bothered comparing the difference on prints. Maybe I should.

I'm puzzled that I cannot get Qimage to interpolate ppi to 720. It's always 360ppi (on my Epson 7600) with settings at maximum micro detail. But I have noticed that in certain circumstances it has interpolated an image to 720ppi in the past, but I can't remember what the conditions were. Not that it really matters. The great thing about Qimage is that it does all the work. The default settings have always seemed to be very acceptable to me.
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Dale_Cotton

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resizing images
« Reply #42 on: February 17, 2006, 12:16:42 pm »

Quote
Gordon,
I'm puzzled that I cannot get Qimage to interpolate ppi to 720. It's always 360ppi (on my Epson 7600) with settings at maximum micro detail. But I have noticed that in certain circumstances it has interpolated an image to 720ppi in the past,[a href=\"index.php?act=findpost&pid=58405\"][{POST_SNAPBACK}][/a]
To the best of my knowledge all Epson wide format (ink lines) printers have a native res of 360 and all their smaller (piggyback cartridges) printers, 720. This is not mentioned on the QImage quality comparison page.
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drew

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resizing images
« Reply #43 on: February 17, 2006, 12:27:58 pm »

Gordon,
I have to say I am not great advocate of sharpening for output. I tend to capture sharpen Canon digital files a bit in C1 Pro and I sometimes capture sharpen film scans when scanning with an Imacon precision II. I have Photokit Sharpener and I am familiar with other Photoshop methods such as the one John Brown described a few years ago on this website. I have never tried sharpening with Qimage and I tend to use it at default settings. All I can say is that I like my prints and I hope others do too. I particularly like them to look like my favourite wet prints from film.
I think sharpening is one of the most written about and abused tools in the digital box.
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Andrew Richards [url=http://www.andrewri

Stephen Best

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resizing images
« Reply #44 on: February 17, 2006, 12:44:20 pm »

Just to throw in more variables ...

I've been playing with the Lightroom beta with some raw files from a mate's Canon 5D. Lightroom has an option for "Print Resolution". I printed the same image with the Print Resolution set at 240dpi and 360dpi, deliberately leaving Enable Print Sharpening off. On Enhanced Matte at 2880dpi unidirectional, the 360dpi print was easily superior. The print sizes were chosen to ensure at least 360ppi of input data (the larger the print size is pushed, the smaller the differences one would expect). Assuming the algorithms stay the same for the shipping product, I can't see a reason why anybody would chose 240dpi. I haven't yet played around with any other values, nor compared this to what I can get out of Photoshop.
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Ray

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« Reply #45 on: February 17, 2006, 08:02:57 pm »

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To the best of my knowledge all Epson wide format (ink lines) printers have a native res of 360 and all their smaller (piggyback cartridges) printers, 720. [a href=\"index.php?act=findpost&pid=58408\"][{POST_SNAPBACK}][/a]

Thanks Dale. That must be the explanation. I've been using my old 1290 printer mostly for web pages and letters for a while now. However, there must have been an occasion recently when I used it for a print from Qimage and noticed the 720ppi interpolation.
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Gordon Buck

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« Reply #46 on: February 17, 2006, 10:00:32 pm »

Thanks to those answering my question about when to sharpen in Qimage.  I played around with Qimage once and found it useful for panoramics but then, as now, I was confused about final sharpening.

Part of my confusion is that I've bought into the Photokit Sharpener idea of capture, creative and output sharpening.  It just made so much sense to me that I bought the package after very little testing and I've made almost no comparisons since then.  I like and use Photokit Sharpener (I have no relationship with the company other than satisfied customer).

My routine workflow includes saving what I call a "pre-print" image and I even include "preprint" in the file name. That is,  an image ready to print except for final sharpening.  I suppose I could just trust Qimage to apply the appropriate sharpening but don't have the confidence to do so and don't want to do the testing to build up that confidence; hence, my question.

Qimage seems to be a good product and I do subscribe to the idea of (usually) not uprezing for larger prints so that aspect of Qimage is very interesting.  And Drew's comparisons certainly have caught my eye...
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Gordon
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Ray

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resizing images
« Reply #47 on: February 17, 2006, 10:19:32 pm »

Quote
I suppose I could just trust Qimage to apply the appropriate sharpening but don't have the confidence to do so and don't want to do the testing to build up that confidence; hence, my question.
[a href=\"index.php?act=findpost&pid=58445\"][{POST_SNAPBACK}][/a]

Gordon,
No need to trust Qimage to do the final print sharpening. You can simply turn it off. There's a row of little boxes at the foot of the print preview.

However, I see the problem here if you are using Photokit Sharpener. In order to apply the final sharpening for the print size, you presumably have to rez up the image to it's final size and ppi first, in which case you are already doing the work that Qimage does for you automatically.
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