Can you emulate camera pixel shift with multiple shots and software?

Asked 10/2/2018

5 views

2 answers

0

I’m interested in post-processing methods that might mimic the noise reduction and detail gains of built-in pixel-shift modes (such as on some Sony and Pentax cameras) in situations where pixel shift normally works well: tripod, static subject, no wind, and enough time for several exposures.

Ideas I’ve considered:

  • taking 4 identical shots and averaging them for lower noise
  • introducing slight movement between shots and using super-resolution methods
  • shooting a 2x2 stitched panorama with a longer focal length

The tradeoffs seem to be that simple averaging reduces noise but doesn’t add real detail, while super-resolution and pano approaches become more cumbersome. Is there a reasonably simple and effective workflow or software approach to approximate pixel shift from multiple images, especially starting from raw files?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

7y ago

2 Answers

1

The easiest way to get what you want is to use a camera with the feature built-in. Most tasks tend to be more cumbersome and time-consuming to do in post-processing than the same tasks in-camera.

If dpreview's description of Dynamic Pixel Shift is accurate, you should be able to take four hand-held shots, align, resize, and average them to produce equivalent results.

When using Dynamic Pixel Shift, image stabilization is switched on by default (a giveaway that it isn't doing single pixel shifts like its tripod-mounted counterpart) and the camera relies on the natural movement or shake of the photographer for four slightly different images. Stabilization remains on to ensure there is not too much of a framing difference between shots. The four files are then aligned and combined to produce one 'super resolution' image with increased detail, dynamic range and lower noise. Without getting into too much detail, sampling a scene multiple times with slight shifts to the image allows details to be localized with sub-pixel precision (since shifts are unlikely to be perfect multiples of one pixel).

I would use align_image_stack and ImageMagick. Here's how to create a super resolution photo with any camera describes using Photoshop. It also seems that using many more than four images is unnecessary.

Interestingly, the difference between the 4 image and 20 image super resolution examples is less noticeable. While there is some advantage to stacking more images, returns are diminishing in this case.

See A Look at Reducing Noise in Photographs Using Median Blending.

Originally by user75526. Source · Licensed CC BY-SA 4.0

user75526

7y ago

0

AI Answer

Generated from our catalog & community — verify before relying on it.

Only partially. You can imitate some benefits of pixel shift, but not as simply or as reliably as a camera with true built-in pixel shift.

What works:

  • Averaging several aligned shots reduces random noise.
  • If you capture several frames with tiny natural shifts between them, software can align and combine them for a super-resolution-style result.
  • A practical workflow is to shoot multiple frames, stack them as layers, upscale, auto-align, then average/merge.

What doesn’t fully translate:

  • Four identical shots won’t reveal extra scene detail by themselves; they mainly improve noise.
  • True pixel shift deliberately moves the sensor by exact sub-pixel amounts, often helping color sampling and detail in a way ad-hoc post methods can’t precisely duplicate.
  • Panorama stitching with a longer lens can increase resolution, but it changes shooting geometry and can complicate depth of field.

So yes, multi-image super-resolution can approximate some of the effect, but it’s more cumbersome and generally less exact than native pixel shift. If simplicity is the priority, the closest DIY approach is a short burst of nearly identical images with slight natural movement, followed by alignment and averaging/merging in software.

UniqueBot

AI

7y ago

Your Answer