Tag Archive for image

On upgrading from Fedora 13 to Fedora 14

November 7, 2010 No comments

My Fedora box recently got upgraded to the latest version of the distribution (14) and I stuck to a method that I have used successfully before and one that isn’t that common with variants of Linux either. What I did was to go to the Fedora website and download a full DVD image, burn it to a disk and boot from that. Then, I chose the upgrade option from the menus and all went smoothly with only commonplace options needing selection from the menus and no data was lost either. Apparently. this way of going about things is only offered by the DVD option because the equivalent Live CD versions only do full installations.

However, there was another option that I fancied trying but was stymied by messages about a troublesome Dropbox repository. As I later discovered, that would have been easily sorted but I went for a tried and tested method instead. This was a pity because only two commands would have needed to be issued when logged in as root and it would have been good to have had a go with them:

yum update yum
yum –releasever=14 update –skip-broken

These may have done what I habitually do with Ubuntu upgrades but trying them out either will have to await the release of the next version or my getting around to setting up a Fedora virtual machine to see what happens. The latter course of action might be sensible anyway to see if all works without any problem before doing it for a real PC installation.

Linux, Software

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A tendency for overexposure?

July 14, 2010 No comments

A recent trip to Sweden saw my Canon PowerShot G11 being put to rather more use than was expected. If I had known what might have been coming my way, I may even have eschewed the principle of lightweight packing to bring along my Pentax DSLR. Nevertheless, the little Canon did what ever was asked of it when light was plentiful.

Once thing that I have noticed in comparison with the Pentax is the Canon’s tendency to overexpose a scene. To a point, this can be explained by the former having proper spot-metering and the latter having the less specific partial metering. In fact, that might explain why a Canon EOS 10D SLR in my possession has the same tendency. Maybe it’s time to make more use of the Sekonic light meter that I have but that adds bulk that doesn’t fit in with the idea of carrying a compact camera around with you.

That leaves getting more practice with exposure corrections at processing time (I do capture all my photos in raw format). Going further, I am finding that the same consideration appears to apply to image sharpening too. It’s almost as if you need to develop a feeling for the results produced by a camera before satisfaction with any acquired photos will follow. Having decent lighting at capture time and not having muck on the sensor helps too as I have discovered with the photos made used my Pentax K10D on a recent visit to Arran and Argyll. The state of the sensor needs sorting (even if it has an anti-dust system on board) but I sometimes wonder if my judgement of lighting is what it used to be or whether my aspirations have gone too high. Maybe I need to slow down a little so as to set aside time for working on getting better results and with the right light, a quantity that should come with autumn and winter. In the meantime, I’ll stick with making the best of the British summer.

Photographic Equipment

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Easier to print?

February 20, 2010 No comments

One matter that really came to light was how well or not the pages on here and on my hill walking and photography website came out on the printed page. After spotting a WordPress Codex article and with an eye on making things better, I have made a distinction between screen and print stylesheets. The code in the XHTML looks like this:

<link rel=”stylesheet” href=”/style.css” type=”text/css” media=”screen” />
<link rel=”stylesheet” href=”/style_print.css” type=”text/css” media=”print” />

The media attribute seems to be respected by the browsers that I have been using for testing (latest versions of Firefox, MSIE and Opera) so it then was a matter of using CSS to control what was shown and how it was displayed. Extraneous items like sidebars were excluded from the printed page in favour of the real content that visitors would be wanting anyway and everything else was made as monochrome as possible with images being the only things to escape. After all, people don’t want to be wasting paper and ink in this cash strained times and there’s no need to have any more colour than necessary either. Then, there’s the distraction caused by non-functioning hyperlinks that has inspired the sharing of some wisdom on A List Apart. Returning to my implementation, please let me know in the comments what you think of what I have done on here and if there remains any room for improvement.

Web Development

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8?

October 12, 2009 No comments

It now seems that we have a new version of Photoshop Elements from Adobe for every year unless you’re a Mac user. Version 7 convinced me to splash out and that gained me Camera Raw recognition of my Pentax K10D along with subtly enhanced image processing power that I have been putting to good use to get more pleasing results than I ever got before. What can be achieved by using levels, curves and the shadow/highlight adjustment tool for exposure correction has amazed me recently. Quick selection functionality has allowed me to treat skies differently from everything else in landscape photos, a flexible graduated filter if you like. It seems to work on Windows 7 along with Vista and XP so I plan to stick with it for a while yet. As you may have gathered from this, it would take some convincing to make me upgrade and, for me, version 8 doesn’t reach that mark. All in all, it seems that it is a way of giving Mac users a new release with added goodness after having to stay with 6 for so long; yes, there are new features like autotagging in the image organiser but they just don’t grab me. Given that they already have Aperture from Apple and Windows users seem to get more releases, it’s a wonder that any Mac user would toy with Elements anyway. Maybe, that’s Adobe’s suspicion too.

Graphics, Imaging, Software

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Getting Fedora working in VirtualBox

May 12, 2009 No comments

After a hiatus induced by disk errors seen on start up, I have gone having a go with Fedora again. In the world of real PC’s, its place has been taken by Debian so virtualisation was brought into play for my most recent explorations. I could have gone with 10, the current stable version, but curiosity got the better of me and I downloaded a pre-release version of 11 instead.

On my way to getting that instated, I encountered two issues. The first of these was boot failure with the message like this:

FATAL: INT18: BOOT FAILURE

As it turned out, that was easily sorted. I was performing the installation from a DVD image mounted as if it were a real DVD and laziness or some other similar reason had me rebooting with still mounted. There is an option to load the hard disk variant but it wasn’t happening, resulting in the message that’s above. A complete shut down and replacement of the virtual DVD with a real one set matters to rights.

The next trick was to get Guest Additions added but Fedora’s 2.6.29 was not what VirtualBox was expecting and it demanded the same ransom as Debian: gcc, make and kernel header files. Unfamiliarity had me firing up Fedora’s software installation software only to find that Synaptic seems to  beat it hands down in the search department. Turning to Google dredged up the following command to be executed and that got me further:

yum install binutils gcc make patch libgomp glibc-headers glibc-devel kernel-headers kernel-devel

However, the installed kernel headers didn’t match the kernel but a reboot fixed that once the kernel was updated. Then, the Guest Additions installed themselves as intended with necessary compilations to match the installed kernel.

The procedures that I have described here would, it seems, work for Fedora 10 and they certainly have bequeathed me  a working system. I have had a little poke and a beta of Firefox 3.5 is included and I saw sign of OpenOffice 3.1 too. So, it looks very cutting edge, easily so in comparison with Ubuntu and Debian. Apart from one or niggles, it seems to run smoothly too. Firstly, don’t use the command shutdown -h now to close the thing down or you’ll cause VirtualBox to choke. Using the usual means ensures that all goes well, though. The other irritation is that it doesn’t connect to the network without a poke from me. Whether SELinux is to blame for this or not, I cannot tell but it might be something for consideration by the powers than be. That these are the sorts of things that I have noticed should itself be telling you that I have no major cause for complaint. I have mulled over a move to Fedora in the past and that option remains as strong as ever but Ubuntu is not forcing me to look at an alternative and the fact that I know how to achieve what I need is resulting in inertia anyway.

Linux, Software, Virtualisation

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Harnessing the power of ImageMagick

October 26, 2008 No comments

Using the command line to process images might sound senseless but the tools offered by ImageMagick certainly prove that it has its place. I have always been wary of using bulk processing for my digital photo files (some digitised from film prints with a scanner) but I do agree that some of it is needed to free up some time for other more necessary things. With this in mind, it is encouraging to see the results from ImageMagick and I can see it making a major difference to how I maintain my online photo gallery.

For instance, making thumbnail images for the gallery certainly seems to be one of those operations where command line bulk processing comes into its own and ImageMagick’s own convert command is heaven sent for this one. For resizing images, all that’s needed is the following:

convert -resize 40% input.jpg output.jpg

Add a spot of further shell scripting and even a dash of Perl and the possibilities for this sort of thing become clearer and this is but the pinnacle of the proverbial iceberg. The -rotate switch will do what the name suggests and there are a whole plethora of other options on tap. So long as you have Ghostscript on your system, conversion of graphics to Postscript (and Encapsulated Postscript too) and PDF files is possible with the -page option controlling the margin around the image itself in the resulting outputs. Unfortunately, portrait is the sole orientation on offer but a bit of judicious post processing will turn things around. Here’s a command that’ll do the trick:

convert -page 792×612+72+72 input.png ps2:output.ps

For retrieving image metadata like its resolution and size, the identify command comes into play. The -verbose option invokes the output of all manner of image metadata so using grep or egrep is perhaps advisable, especially for bulking processing with the likes of Perl. Having the ability to stream image metadata makes loading databases like MySQL less of a chore than the manual data entry that has been my way of doing things until now.

Graphics, Imaging, Linux, Software, UNIX

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