OT: How to make/use Sony PixelShift images?

[David W. Jones]

Does anyone on the list know anything about processing PixelShift images in Linux graphics applications like RawTherapee?

I've found scattered steps on handling them in RT, but nothing beyond processing the individual images. Nothing about combining them.

I just got a Sony A7R IVA camera. I've taken PixelShift images with it; the camera outputs a RAW file for each shift of the sensor. Somehow the Windows/Mac Sony software combines those into a single, much higher resolution image that I'm hoping to use in Hugin and other Linux software.

This isn't particularly connected with Hugin, although I tried feeding the resulting frames into Hugin as an image stack, but Hugin found no control points.

I would like to have fun shooting PixelShift images (240MP!) to use in making panoramas in Hugin.

Ideas?

Thanks.

-- 
David W. Jones
gnome...@gmail.com
wandering the landscape of god
http://dancingtreefrog.com
My password is the last 8 digits of π.

[Lukas Jirkovsky]

On Fri, 19 Jul 2024 at 06:05, David W. Jones <gnome...@gmail.com> wrote:
>
> Does anyone on the list know anything about processing PixelShift images in Linux graphics applications like RawTherapee?

Hi David,
I've repeatedly used make_arq [1] and it worked well for my A7R III so
far. It creates the combined ARQ image. A7R IV should be supported,
too. However, the resulting ARQ is supposedly not compatible with the
original Sony software, which may or may not be a problem. I don't
care about that, because I don't have any windows machine where I
could install the sony's software anyway, but it is something to take
into account if you need interoperability.

> I've found scattered steps on handling them in RT, but nothing beyond processing the individual images. Nothing about combining them.

You can process the resulting ARQ file pretty much the same way as you
would your ordinary ARW files in rawtherapee. If I recall correctly,
the only difference is that you get some additional settings for
demosaicing and motion correction in case there is a movement between
the frames.

I don't know how well the motion correction works though. I've used it
only for static images – scanning negatives to be exact.

Lukas

[1] https://github.com/agriggio/make_arq

[David W. Jones]

Thanks. I finally got it to run, it seems to produce good results even
with handheld shots from my A7R IVA.

[Terry Duell]

Hello David,

On Thu, 2024-07-18 at 18:05 -1000, David W. Jones wrote:
>  
> Does anyone on the list know anything about processing PixelShift images in
> Linux graphics applications like RawTherapee?
>  

I know that RawTherapee handles Pentax pixelshift files OK, but not sure whether
it handles files from other camera manufacturers.
Tom Vijlbrief made a fork of dcraw which he called dcrawps, which handled PS
files from early Pentax cameras, and with Tom's help I extended dcrawps to
include the PS files from later Pentax cameras.
I suspect it wouldn't be difficult to include PS files from other cameras,
provided they were 4 shots i.e. one image for each of the bayer pattern pixels.
One of the nice things about using dcrawps is that you can extract any or all of
the images, and it can make correction for any movement detected, along with all
the neat things dcraw does.
Not the answer to your question but depending on whether you can use the
software provided and whether it does all the things you need it do, you might
think about dcrawps, maybe have a word with Tom (tvijlbrief at google mail).

Cheers,
--
Terry Duell <tdu...@iinet.net.au>

[David W. Jones]

Thank you, Terry. Lucas Jirkovsky (in an earlier reply) referred me to the make_arq Python script and it works very well, once I figured out how to run a Python script. (Not a Python person here.) It handles frames from the A7R IVA without any tweaking. It even handled a 16-frame  PixelShift set!

It's good to know there are alternatives to Sony's non-Linux software for handling their PixelShift images.

Make_arq.py:

https://github.com/agriggio/make_arq

It would be nice if producing a combined PixelShift image could be done in camera. But I know cameras have to output image files in real time, so they can't spend a chunk of dedicated time combining the frames. I wish they did that instead of waste their processing power on AI-based image processing!

[Sam Rhoads]

I’m sorry if this is the wrong way to ask, but I am trying to find out how to ask for advice concerning using Hugin to put together a panorama for SkySafari. Years ago I used Hugin to create a panorama for SkySafari but now I want to do it again, but this time I need to take the pictures from eight different places on my condominium rooftop (because there’s a large structure on the roof) and then stitch them together.

Please someone tell me how I should ask for help.

Thanks and aloha,

Sam Rhoads


> On Jul 21, 2024, at 2:47 PM, David W. Jones <gnome...@gmail.com> wrote:
>
> 

[David W. Jones]

On 7/21/24 18:14, Sam Rhoads wrote:
> I’m sorry if this is the wrong way to ask, but I am trying to find out how to ask for advice concerning using Hugin to put together a panorama for SkySafari. Years ago I used Hugin to create a panorama for SkySafari but now I want to do it again, but this time I need to take the pictures from eight different places on my condominium rooftop (because there’s a large structure on the roof) and then stitch them together.
>
> Please someone tell me how I should ask for help.
>
> Thanks and aloha,
>
> Sam Rhoads

Hmm, you'll have to optimize your panorama for Translation. That's how
Hugin handles your situation, where the camera moves between photos.
It's not something I've done much of, I'm sure other folk on the list
are better resources about that.

[wirz]

Hi Rhoads,

On 22/07/2024 10:05, David W. Jones wrote:
> On 7/21/24 18:14, Sam Rhoads wrote:
>> I’m sorry if this is the wrong way to ask, but I am trying to find out
>> how to ask for advice concerning using Hugin to put together a
>> panorama for SkySafari.  Years ago I used Hugin to create a panorama
>> for SkySafari but now I want to do it again, but this time I need to
>> take the pictures from eight different places on my condominium
>> rooftop (because there’s a large structure on the roof) and then
>> stitch them together.
>>
>> Please someone tell me how I should ask for help.
>>
>> Thanks and aloha,
>>
>> Sam Rhoads
> Hmm, you'll have to optimize your panorama for Translation. That's how
> Hugin handles your situation, where the camera moves between photos.
> It's not something I've done much of, I'm sure other folk on the list
> are better resources about that.
>

I think you'd have to explain your setup a bit. I assume you are taking
photos of the night sky, and anything on earth is irrelevant? Then your
camera is effectively not moving (ie the sky is the same from all
corners of your roof) and you should be able to optimise the pano
without translation. If you are taking photos of a flat surface from
different points of view, you need translation, and if you take photos
of a 3D scene from different points of view there is probably no good
solution.

Apart from that, start a new thread when you have a new question. If
you answer to a different question and change the topic that will be
displayed wrongly for some people.

cheers, lukas wirz

[Samuel Rhoads]

Thanks Lucas. I will try to start a new thread and explain what I want to do I’m trying to attach the panorama that I took 12 years ago. Now I want to do something similar I don’t yet know how to start a new thread but I’ll try to figure that out.