Panasonic Lumix DMC ZS-100 - aspect ratios in JPEG and raw outputs

[Doug Kerr]

I guess this is the right forum for this.

In a thread in another section, there has been considerable discussion about the implications of various "aspect ratio" settings in the camera and the sensel dimensions of a raw file, especially in the context of the Fujifilm GFX 100RF camera. This note gives some corresponding information for the Panasonic Lumix DMC ZS100 camera

The Panasonic Lumix DMC ZS100 is a compact camera with a "1 inch" sensor and an inbuilt zoom lens. One can choose for the camera to deliver a JPEG file (with a choice of resolutions) only, a raw file only, or a raw file plus a JPEG file (with a choice of resolutions). It is the camera I use for most of my photography these days.

The sensor has an aspect ratio of 3:2 (5472 px × 3648 px for the delivered image). The camera offers the following settings for aspect ratio. This only affects the JPEG output file (if any).

3:2, 4:3, 16:9, 1:1

All those choices other than 3:2 involve a crop of the image in the JPEG file (if taken) in one direction or the other.

In every case, the viewfinder shows the portion of the taken frame that would appear in a JPEG file of the aspect ratio that is set.

In every case, the raw file (if taken) has the same sensel dimensions, 5488 × 3664, and reflects the entire taken frame.

Best regards,

Doug

 

[Ted Cousins]

I guess this is the right forum for this.

In a thread in another section, there has been considerable discussion about the implications of various "aspect ratio" settings in the camera and the sensel dimensions of a raw file, especially in the context of the Fujifilm GFX 100RF camera. This note gives some corresponding information for the Panasonic Lumix DMC ZS100 camera

The Panasonic Lumix DMC ZS100 is a compact camera with a "1 inch" sensor and an inbuilt zoom lens. One can choose for the camera to deliver a JPEG file (with a choice of resolutions) only, a raw file only, or a raw file plus a JPEG file (with a choice of resolutions). It is the camera I use for most of my photography these days.

The sensor has an aspect ratio of 3:2 (5472 px × 3648 px for the delivered image). The camera offers the following settings for aspect ratio. This only affects the JPEG output file (if any).

3:2, 4:3, 16:9, 1:1

All those choices other than 3:2 involve a crop of the image in the JPEG file (if taken) in one direction or the other.

In every case, the viewfinder shows the portion of the taken frame that would appear in a JPEG file of the aspect ratio that is set.

In every case, the raw file (if taken) has the same sensel dimensions, 5488 × 3664, and reflects the entire taken frame.

Best regards,

Doug

What was your expectation, Doug?

Panasonic cameras can vary as to raw size. For example, their DMC-GH1 shoots different aspect ratios but with a constant diagonal size so the raw file sizes vary accordingly.

https://www.dpreview.com/reviews/panasonicdmcgh1

 

[Doug Kerr]

Hi, Ted,

What was your expectation, Doug?

That was just what I expected.

Panasonic cameras can vary as to raw size. For example, their DMC-GH1 shoots different aspect ratios but with a constant diagonal size so the raw file sizes vary accordingly.

I have not looked into that camera (I don't have one). That is very interesting.

Thanks.

Best regards,

Doug

 

[Doug Kerr]

Hi, Ted,

I am a bit surprised that, in the only reference I have so far found that states the sensel dimensions of the DMC GH1 raw files for the four aspect ratios, the sensel dimensions are exactly the same as the pixel dimensions stated for the JPEG images (highest image quality) from those aspect ratios.

We ordinarily see the sensel dimensions of the raw file being a dozen or so sensels in each direction greater than the pixel dimensions of the largest JPEG image. That is in part a requirement of the demosaicing algorithm which, in "developing" each pixel of the image, needs to consider the sensel values for some distance in every direction from the location of that pixel. Thus to develop the pixel near the edges of the image, sensel values a bit father out are required. And there are other needs for those "marginal" sensels.

Best regards,

Doug

 

[Doug Kerr]

Hi, Ted,

Ah, yes,

Based on some sample raw files found on dpr:

For the DMC-GH1, in apparently the 4:3 aspect ratio mode, where the highest quality JPEG image is 4000 × 3000 pixels, the raw file seems to have sensel dimensions of 4060 × 3016 sensels (16 "extra" in each direction).

In apparently the 16:9 aspect ratio mode, where the highest quality JPEG image is 4352 × 2448 pixels, the raw file seems to have sensel dimensions of 4368 × 2464 sensels (again, 16 "extra" in each direction).

Makes sense.

Best regards,

Doug

 

[Doug Kerr]

It may well be that for the Panasonic DMC-GH1, the "workable" sensor area is about 4368 × 3016 sensels.

The extracts from this for the various aspect ratios support development of JPEG images with a consistent diagonal dimension of about 5000 px, except for the 1:1 aspect ratio, where that is a bit less (4231 px). (To have attained that diagonal size for the 1:1 aspect ratio would have required the workable height of the sensor to be about 3551 sensels.)

Very neat scheme.

If we base our reckoning of angular field of view on the frame diagonal (as is common), then this means that for a given lens focal length, the angular field of view will be essentially the same for any aspect ratio choice. This is cited as advantageous. I think that in reality it is at best "tidy".

Best regards,

Doug

 

[GarethKitchener]

I have a Panasonic DMC-TZ70, which is the camera I take with me when I don't want to take a camera with me. (!)
As far as I can remember, the default aspect ratio is 4:3. That uses the full sensor and all the other options are crops.
The raw files reflect the aspect ratio selected.