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Google open-sources extreme JPEG compression

18 Mar

I previously criticised JPEGmini, a commercial program that promised to reduce JPEG size by focusing on the way humans perceive colour. My repeated finding in using the program was that it was unable to provide better compression than GIMP’s JPEG export – and GIMP is free!

Now Google has fielded Guetzli, a new JPEG compression engine that Google describes as drawing on psychovisual research. So in that aspect, it doesn’t sound much different from JPEGmini. It is, however, open-sourced, and according to Google, promises 35% smaller files compared to the open source JPEG library libjpeg, which without much doubt must be the engine used by GIMP.


Original on the left, libjpeg, center, and Guetzli on the right. Google notes the paucity of blocky artefacts in the Guetzli output, but I would also note the loss in vibrance, a typical approach in noise reduction.

Guetzli, like other recent advances in imaging, is slow. So slow, in fact, that it sounds like its use case is currently limited to very frequently downloaded items like website banners, where spending a lot of time optimizing will considerably reduce traffic.

Alternatively, though, Google could put its weight behind FLIF, supporting it in Chrome/Chromium and thereby putting pressure on other browsers to also support it. FLIF promises to provide current-best lossless compression and is interlaceable – and open source.

Guetzli might give a smaller file than FLIF, but only with more lossy compression, and it sounds like it’s currently a lot slower (I have seen no figures comparing the two).

From photographers’ perspectives, Guetzli may have one further use case. Images with such highly optimised compression are unlikely to be very usable for further editing, so for showing off your work on the web while spoiling the fun for potential thieves, Guetzli or any higher-compression tool might be a good choice (but remember – Google can “guesstimate” the image back with RAISR).

Pentax’ PLM and DC lenses explained

2 Mar

DC (“direct current”) is a kind of focus motor that has been used in Pentax lenses for some time. While it is quiet, it’s not entirely silent. Pentax’ most recent 55-300mm lens features a new type of motor branded as PLM. Here is what Pentax representatives had to say about it in an interview:

The PLM design can quickly activate and allow for faster focusing, but the lens element must be low weight due to limited power (torque).

The DC motor can generate high power (torque) with deceleration mechanisms, which is better for lenses with larger focusing elements. A DC motor can be driven at high speed, but there is an issue that a little sound is generated.

Generally, we use the what we feel is the best focusing mechanism for each specific lens design.

It would be reasonable to suspect that the 55-300mm’s new optical formula and narrower aperture were needed to allow the faster, silent motor to be used, although it should be noted that, like the recent 18-50mm kit and non-kit zoom lenses, the new 55-300mm lens is collapsible to a somewhat smaller size, with the difference between collapsed and uncollapsed size being more pronounced in the 18-50mm.

In the interview, the representatives went on to explain that they do not expect to see PLM in a large aperture lens any time soon, instead putting their money on researching other kinds of motors as well as algorithms to improve autofocus.

Sony a99 II: No C-AF in manual video?

15 Feb

Here’s the relevant section of Kai Man Wong’s review of the a99 II, discussing its video capabilities, the f/3.5 caveat, and the missing option to have continuous autofocus when video exposure is set manually:


I take my hat off to Kai for delivering a more thorough review of this camera, and in a shorter space of time, than other frequented outlets.

Yongnuo 85/1.8 with better bokeh, less CA and noisier AF than Canon

12 Feb

For full details, see the video by Christopher Frost, below:


The breakfastographer’s opinion based on the samples shown is that the bokeh is nicer and the CA much lower in the Yongnuo. Corner sharpness is worse, though, and the autofocus has various issues described in the video. No statement was made about focus throw, but it seems to be okay, so manually focusing is an option. At a price of half the Canon, it’s cheaper than a Samyang/Rokinon/Bower/etc., which would also provide only manual focus.

In spite of the corner softness, it’s sold as a full frame lens, and its value proposition as a portrait lens is hard to beat on that format. If you do want to go cheaper, there are 50/1.8 options for APS-C cameras for just over a 100 eurodollars, but bokeh will be better with the 85/full frame combination – or really 85 on any format!

Did DigitalRev TV foreshadow the KP?

6 Feb

I may have more to say on what’s recently happened to DigitalRev TV on another occasion, but here’s a soundbite from Kai in May 2011, a good five and a half years prior to the announcement of the Pentax KP:

I think if they made something which looked kind of retro and cool, that would be really good. I think I’m jizzing my pants if they made this kind of a silver and black, made it look a bit like your OM-1, that would be great.

That’s a reference to Lok’s father’s OM-1, which Lok showed off in the preceding segment of the video. In a mock charity donation video for Pentax, Kai’s presumably scripted voice-over continues:

help Pentax be a pioneer again … help them think different and create a create a retro cool DSLR that will make the world a better photographic place

They added this photoshopped image:


And this is what Pentax came out with:


And here is an actual OM-1:


Released under CC-BY-2.0 license by Flickr user E Magnuson

Design similarities:

  • Pyramid prism housing, rather than various other shapes used by Pentax over the years
  • Protruding strap attachment points (rather than recessed as used on Pentax’ mid-range models); Ricoh left off the triangular piece for the photo, but it is usually included in the box
  • Control elements on the front and top plate in almost exactly the same places

Oh, and it comes in silver, with all the same parts in silver that would be so on a traditional SLR like the OM-1:


Well, what do you make of it? Coincidence? Inevitability? Inspiration?

And would this have been a better design to release in February 2012, less than a year after DRtv’s video, instead of the K-01?

DPReview forgets Sony RX10 III has stacked CMOS, concludes lens is improved

26 May

I’m not even sure I should wait on them to figure out why they got the result they got, it seems they’re quite content with it, as are their commenters. I don’t know what massive electromagnet they engaged in North America, but it’s working. I thought about making popcorn, but figured out I might end up obese before they figure out what’s really going on.

They seem to understand that Pentax’ pixel shift improves resolution, so no idea why they’re having problems now.

Link to article about RX10 III (if you want)

Hasselblad Masters to wait eight months for their prizes

16 Jan

Hasselblad has announced the winners of its Hasselblad Masters 2016 competition, but they’ll have to wait until photokina in September to receive their prizes – a new Hasselblad medium format camera each. Perhaps this means that Hasselblad will announce a new camera at the trade show, which might be worth the wait – after all, we were promised that the time of whimsical management decisions at Hasselblad (Lunar, Stellar, HV) were over.