yamahito

Matt is a respected security researcher who has a rare gift of communicating his field.

I’m lucky to be rather tenuously associated with him through a website his partner created and runs, on which I am a (seriously lapsed) moderator. Every now and again something goes disasterously wrong with the server hardware and we get a little email from him to remind us of his presence. Usually something along the lines of ‘I fixed it, it’s working now’.

Matt is almost entirely unknown about by the frequenters of the website he has done a lot to maintain over the years; occasionally one of us comes across his name in his professional context, given that there are a fair few computer profesionals around on the web, but generally these little emails serve as the only reminders of what Matt does.

And what Matt does is interesting. Moreover, Matt has the rare gift of being able to talk about what he does and make it sound interesting. You should go have a little look at his site and his blog that’s up there - hopefully he’ll get around to writing more of it sometime in the future.

I was recently asked to disable internet access on a suite of macs for an exam. Easier said than done: I don’t have any router/firewall control for the network they’re on, and they would still need network printing access.

There were a few things I could have done: blocking port 80 and 443 on the machines’ local firewalls, or changing the proxy settings to point the web browsers to some bogus proxy. Problem is that the machines will need internet again within minutes of the end of the exam, and I’m just not confident enough that changing such settings won’t bugger something up.

So I went down a different route: this is a script for running at the start of an exam. It only runs on a management server with Remote Desktop, so no worries about buggering up the client machines. It monitors the current application of each machine, and if someone runs firefox or safari, it will log their machine name, the application, and the timestamp, then bring up an observation window on their computer.
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…Is that they expect you to make a decision without enough information.

Work has a subscription to MacUser that normally ends up on my desk, and I always enjoy reading Howard Oakley’s column and the emails there. He can sometimes be a bit curmudgeonly, as a computing veteran, but I think he’s raised a good point here that’s equally applicable to pretty much any OS or browser out there.

Moreover, the point is based on what should be a fundamental principle of computing: too often developers these days are getting carried away with some technical idea without considering the pragmatic needs and concerns of the end user. It can be difficult to take that step back to gain some perspective if you relish getting your hands in the guts of the technology you work with. My problem tends to be the other way - brainstorms and careful consideration often results in great ideas that never go anywhere because I don’t have (or make) the time to get stuck in.

I’m sure it wasn’t long ago that a ‘mash-up’ was a seamless mix of two existing songs, but these days it seems to be taking on a different meaning in web design.

The name of the game, it seems, is taking elements from all those wonderful web-sites we belong to now, and mixing them together in some sort of portal/web-application.

Hmm… my latest flickr pictures and blog entries together with facebook information on a home page I’ve been meaning to write… Could be good, if it’s done right.

Honestly, I don’t know if it’s a useless fad or the next stage of web evolution. But Microsoft has jumped onto the bandwagon with Popfly.

Lots of people see me as some sort of ‘Mac geek’ (despite the fact that 95% of all my computing happens on a windows PC (for the moment)). Others are struck by my linux advocacy for servers. The truth is I don’t feel I’m particularly anti-Microsoft or pro-apple/linux. All of the current OS options out there grind my gears at some point or another, and all I want is to get the best of all possible worlds. But I do have some ‘automatic reservations’ about products from any software house based on previous experience, so I’m going to list a couple of MS-centric ones:

Microsoft have traditionally followed very closed-source development philosophies. When I say that, I’m not talking about the fact that their software is closed source, or that they charge too much for it: I really don’t think that they’re doing anything there that isn’t their right to do. The problem is that it extends to proprietary file formats and communication protocols and the like. And MS aren’t alone in this: real player, AOL Instant messanger, the list goes on.

One of the reasons I like how apple and google have changed in the last decade is that they will embrace open standards, even though their software is closed source. It means it’s easier to move data around different platforms, different clients… and rather than losing business, it seems to increase their market share. I think that this attitude will prove to be more successful in the long run.

So I’m a little cautious about popfly from MS - and also a little surprised, in a good way. I’m hoping that it will be a little gleam of Microsoft’s past glories - not a big invention, but a piece of useful innovation.

Following on from part 1

The left column are reference images: the original at the top, then an orangy duotone, then an orange/green tritone.

The middle column: at the top, a blue colorization layer, then the two duotones, all applied in a Hue blend mode.

The right column is the same as the middle column, but is using marcus’ technique (technique 3 from part1) to desaturate the less colourful parts of the images. This also eliminates the colour casts from the shadows and the chips in the background wall.

If the above interested you, you can have a look at the full size image (>2MB jpeg).

Following on from my photoshop vibrancy challenge, I thought I would talk about some photoshop techniques I’ve been playing with for changing the saturation on photographs. All thumbnails are clickable.

Original shot

Apologies to my niece Megs: I took this photo without letting her pose for it with the result that she doesn’t have some fake grin and posture in it

Technique 1: Colorize in Hue Mode

a simple but effective technique I picked up last summer:

Create a HSB adjustment layer, colorize, then use the ‘hue’ blending mode.

the greys are desaturated, and although the tone is monochrome, you retain some of the depth and range of the original.

Technique 2: Duotone in Hue Mode

The first image here is the tritone, included for reference.

Once you’ve created a duotone (or tritone in this case), you can copy it back as a layer to the original, again setting it to a Hue blending mode.

The duotone gives you an extra element of control over method 1 because it allows you to define the colour at different ranges (i.e. curves of shadows, midtones & highlights). However, you can clearly see that the resultant colours can’t be judged by those of the tritone you’re using: compare the colours here to the previous image in the set (the very tritone used to set the hues).

Technique 3: Using a Saturation-based Mask

Here’s the fun bit: thanks for my friend Marcus for the first part of the recipe.

We’ve created a channel based on the saturation of the original image and used it as a mask for a HSB desaturation of -90.

This is perhaps not the best sample image to show the effect (which loses a lot of effectiveness at small sizes), but if you look closely you can see that the center of the daisy is still a bright yellow.

‘Saturation Channel’ Recipe (Tom’s version of a Marcus original):

1. Duplicate the layer(s)
2. Hide the original layer(s)
3. add a layer of solid red, blend mode Hue
4. add a layer of solid red, blend mode Luminosity
5. Flatten visible (this should leave you with an image that goes from gray to red).
6. Use the channel mixer: I used red+150 constant-30 with the monochrome option checked to give a grayscale result
7. copy the layer and paste it into the quickmask to create a selection
8. Save the selection.

In this particular image I mucked about a bit further when using the selection as an image mask with brightness and contrast.

Technique 4: Posterizing the Saturation Mask

The Saturation-based Mask is a basis for a lot of experimentation: In this case, I posterized the mask on the HSB adjustment layer.

I think the result is remarkably subtle.

Thanks to Ian Tindale for the suggestion.

note: I originally posted all of this as a set of six pictures on flickr, but I decided it was wrong there: it cluttered up my photos, used up a valuable set (free accounts only get 3). Besides, I’d want to do a comparison like this, and it’s a discussion, not a portfolio.

So I’ve replacing the flickr stuff with a composite image and a link here.

it always seems that I stop posting more often because I have something interesting to talk about that I want to take my time in posting about. Then nothing else gets posted in case I dislodge the other thing. There’s a moral in there somewhere.

Anyway, something not-as-interesting: I’ve put a lot of old photos up in my photodump. Mainly stuff I took with my first digital camera (a Fuji S602Zoom), but a few bits and pieces that have surfaced from the photo/fileserver consolidation thing I’m doing at the moment.

What, you want a link? It’s right there in the sidebar under ‘photodump’.

I still can’t find my photos from the DBS photography session St3f and I did at Bunsfield the week after the petrol depo there exploded. Grr.

Some of these guys over at Flickr have come up with an interesting effect

It uses a setting called ‘Vibrancy.’ Vibrancy is a Saturation based parameter. As far as I’m aware, this is only available in Adobe Lightroom and the latest Adobe raw converters. I don’t have either of those, so I’m guessing that increasing the vibrancy will preferentially increase saturation of the least saturated parts of an image, whilst increasing the saturation of already heavily saturated parts of the image less drastically.

The effect that the guys on flickr are using involves a decrease in vibrancy, which desaturates all but the most saturated parts of the image, and then an increase in plain ol’ saturation, which normally (or almost normally) re-satuates those parts of the image. In other words, the grey bits get greyer, the bright bits get brighter or stay the same.

The challenge, in a nutshell, is to reproduce this effect with a jpeg.

Bonus marks for explaining to me how to do it with traditional film

Actually, if you can get photoshop to do this, it raises a more general, interesting possibility: “A ‘contrast’ control for the chroma channel” (Ian Tindale’s description of it, not mine)

Ow ow ow… I tripped up running for the little green man at the crossing on the way home from work.

I was holding the new camera.

Touch wood, the damage is limited to a small scuff on the bottom of the body of the camera: I rolled as I fell, but the impact knocked it from my hand.

Worst case scenario is that the casing has buckled slightly, which will cloud the top left of the exposures (bottom right of the camera). I think that’s unlikely though, thanks to the plastic construction of the camera (sometimes plastic’s a good material).

My new film-based SLR body arrived this morning:

(had to take the picture with my shit lens, but you can just about make out my ‘I’m a mac’ mouse - there’s an ‘I’m a PC’ one, too )

One of my work-mates managed to find some old black and white film, so I’ve even taken a couple of snaps - fun fun