Pentax and Sony both have in-camera software that can blend several bracketed exposures and create a High Dynamic Range JPEG. Sony's adds the ability to shoot handheld, with only two exposures needed approximately1/7s apart, with auto alignment of details to merge the shots even if there's a slight shift.

Photo Acute Studio software, a downloadable PC or Mac utility, uses similar intelligence to merge two or more JPEGs or raw files for four different purposes. It has a High Dynamic Range function, but can also double the linear resolution by treating slightly different captures as if they were from a multi-shot back. It can also enhance detail and reduce noise, and merge focus stack sets.

As with lens correction and panorama tools, it uses a database of cameras and lenses that has a familiar failing. No matter how many combinations are added, they never quite keep up with the rate of new cameras and lenses introduced to the market.

But unlike some multi-shot tools, Photo Acute works on raw files and uses Adobe's latest DNG converter. So when Adobe issues an update, Photo Acute gets compatibility with the camera raw format even if it doesn't know everything about it or the lenses involved. It can read the raw files, perform its alignment and pixel averaging magic, then write the result as a DNG file that Adobe Camera Raw and other DNG compatible converters can process.

Some functions can be combined, such as double resolution with HDR. If you do so the size of the resulting DNG can be surprising - a 16-bit DNG raw from a 14 megapixel camera, doubled in linear size, becomes a 56 megapixel monster taking up over 300MB. Even so, on an iMac i7 Quad Core machine it took only two to three minutes to create such files, starting with between two and eight original-source raws.

The optimum for super-resolution, noise reduction or detail enhancement is a set of four or five tripod-mounted shots at the same correct exposure. I tested up to eight, but there is no visible benefit beyond four with most images. If the exposures are bracketed, you don't get the same total elimination of noise in smooth tones like blue sky, and details can take on a slightly over-enhanced look.

Focus stacking only works if the relative planes in the image do not change scale. Macro photographers move the camera on a rack to achieve the desired effect. Very few modern AF lenses refocus without making small changes to focal length; some may suit the technique, most won't. Experiment is the only route to a reliable focus stack workflow.

Applied to wide-angle bracketed views shot handheld, Photo Acute couldn't handle the visible parallax shifts between near foreground and distance. A tripod is essential for any shot with close foreground detail. Distant views, without foregrounds, work well enough steadily handheld. The output will be cropped slightly to allow for small changes in framing.

On or off the tripod, using image stabilisation helps. The stabiliser will cause very small shifts in image position, relative to the Bayer pixel matrix of the sensor. It's these shifts that Photo Acute uses to synthesise higher resolution and eliminate noise. Even without stabilisation, on a tripod, there can be enough movement between frames.

Anything that moves between shots can normally have its "ghosts" removed by selecting the frame from the set on which the conflation is to be based; details in it take priority. There are no layers you can work on to do this manually, and retouching can sometimes be needed.

I felt that my final supersize raws, from 56 to 96 megapixels, didn't really match what you get from a real 60 megapixel back - but you don't put 35mm format zooms on your Phase One P60+.

They definitely showed more detail and texture, with enhanced sharpness to slightly out of focus edges. The difference between interpolating a 12 megapixel raw file up to 17 megapixels directly, and shooting a four-shot set on the 12 megapixel camera to create a 48 megapixel DNG, then sizing that down, was in no doubt.

Two things Photo Acute does really well are to clean up night shots, and enable older pocket digital cameras to yield detailed large images. You can shoot at a higher ISO in low light, making three or four exposures handheld. When combined, the noise is reduced to match a lower ISO setting that would have required a tripod. Mixing files taken at different ISO settings does not work, and tends to make the noise worse rather than better.

My old Konica Minolta Dimage A2 was a favourite raw-capable eight megapixel zoom camera. It's now on Alamy's blacklist along with similar Canon Powershot and Nikon Coolpix models of its period. It can shoot a three-shot raw burst that Photo Acute turns into an unexpectedly sharp 32 megapixel DNG. Many such cameras are included in the Photo Acute database.

Finally, using a PC only (I worked on Mac) Photo Acute can extract a burst of frames from an HD video - either 1280×720 or 1920×1080 on current DSLRs - and synthesise a detailed still capture to double resolution. From that, 2560 ×1440 is useful, and 3840×2160 is comparable to direct output from a six megapixel camera. As long as the frames are of a subject, you'll get something that no in-camera software yet offers.

This returns me to my introduction. What you see now in Photo Acute is a glimpse of the future of in-camera processing. We already have auto-aligned HDR (Sony), single video frame extraction (Nikon), and you can get Photo Acute 60 as an app for mobile devices. In tomorrow's DSLRs, better quality stills will be auto extracted from multiple video frames and enhanced resolution enabled by sensor or lens shift and intelligent alignment of multi-shots.

Photo Acute Studio (the full version with DSLR raw support) costs $119 and can be trialled first.