Saving images,pixel shape ,square or rectangular

[Nick100]

Hi All
It is my understanding that the vast percentage of dslr’s and compact / bridge cameras when shooting photos and not videos will always result in square pixels and not rectangular pixels. When I process I have always observed square pixels. When I save I save as square pixels. Which brings me to the point of this.
For years I have saved my images for overhead projection in what I believe to be square pixels. I am now a member of a new photo club and I am required to save my images as 1440 x 1080 which I believe is a video format and uses rectangular pixels. Therefore I understand that I am being expected to convert square pixels to rectangular pixels and to me this means that in converting I am loosing resolution ,colour quality, and definition in my images because of the change to rectangular pixels
Does anyone have any thoughts
Cheers
Nick

[DanK]

Nick,

I think you are asking the wrong question. unless your image happens to have that aspect ratio (4:3, which is the native aspect ratio of MFT cameras, I think), you can't store in that aspect ratio without either cropping (which will have no effect on pixels) or stretching/compressing. If you stretch or compress one dimension, the image will look wrong.

I would recommend that you re-check what the club requires. My guess is that they are specifying a maximum in each dimension. If not, you will have to crop to the right aspect ratio.

[Manfred M]

Nick - you are heading in the wrong direction here. This club requirement has nothing to do with the shape of the pixels, but rather the number of pixels.

Most clubs use digital projectors to display submitted images and these tend to have a much smaller resolution your camera. Your club wants you to resize your images so the maximum number of horizontal pixels is 1440 and the maximum number of vertical pixels is 1080. You need to resize your images in post processing to meet these requirements. The image size will rarely be exactly 1440 x 1080, so there will be black bars on the edges, just like you get when you display your image on your computer screen and the format you have does not exactly meet your screen resolution.

[xpatUSA]

Hello Nick,

"1440 x 1080 which I believe is a video format and uses rectangular pixels." - I'm not sure that an image size defines the aspect ratio of the pixels. What prompted your thought?

However, some sensors do have rectangular pixels:

https://petapixel.com/2014/11/12/son...pling-sensors/

9.78um x 4.89um!

I've read that other sensors have slightly rectangular pixel active areas - which brings us to the difference between pixel "size" and pixel pitch!

If the pitch is the same vertically and horizontally, no "conversion" is necessary.

Otherwise, going from say an 3:2 aspect ratio image to 1440x1080px (4:3) will require cropping before re-sizing.

HTH.

[edit] others have posted similarly while I was typing ...

[dje]

Hi Nick

1440x1080 is one of the High Definition video formats and is basically 1920x1080 downsized in the horizontal direction only. It is commonly used in TV broadcasting and internet transmision systems because it has a smaller bandwidth. The video file has a flag embedded indicating the aspect ratio is 16:9 (that of 1920x1080) and this lets the TV set or video player know to upsize the video in the horizontal direction to 1920 so that the aspect ratio is correct.

But this technique is not used for still image display to my knowledge. So it's more likely to be as per Dan or Manfred's responses.

Dave

PS Had to look up where Sapphire Beach is. North of Coffs Harbour? Looks like a pretty good place to live!

[Nick100]

Hi All
The reason I have brought this topic up is that for over 10 years while living in Sydney and being a member of a club there we started out using 1080x768 and then changed to 1920x 1080 when we purchased an updated projector and yes I realise that both these sizes were “ nominal” requirements as the projectors would not process accurately images saved outside these dimensions. The 1920x1080 projector could easily accept smaller dimensions but in all the processing I did back then I did not consider that I was ever saving in anything but an image using square pixels .
( I also used to run and organise the projecting of images at almost every club meeting for 6 years ) .
My concern is now, that the information I have been able to find online in many instances indicates that 1440x1080 is a video only format ( and therefore not as good or accurate for still images ) in comparison to other standard formats such as these which I do know are used for video also but can be used for photos

* XGA = 1024 x 768 pixels
* WXGA = 1280 x 800 pixels
* HD = 1920 x 1080 pixels
* 4K = 4096 x 2160 resolution
*
When I look at this website the 1440 option does not exist
https://www.projectorpeople.com/reso...tion-guide.asp

The other anomaly is that nobody is able to give me any explanation as to why 1440x1080 was chosen as the projector and laptop used are both capable of 1920 x1080.

1440 x1080 is actually 1.3333:1 whereas 1920x1080 ,16x9 is actually 1.777777778:1
I do understand that PAR or pixel aspect ratio is different to FAR frame aspect ratio

Another site with information on this topic is below
http://www.frankschrader.us/pixel-as...en-format-169/

I hope this is understandable
Cheers
Nick

[george013]

Hi All
The reason I have brought this topic up is that for over 10 years while living in Sydney and being a member of a club there we started out using 1080x768 and then changed to 1920x 1080 when we purchased an updated projector and yes I realise that both these sizes were “ nominal” requirements as the projectors would not process accurately images saved outside these dimensions. The 1920x1080 projector could easily accept smaller dimensions but in all the processing I did back then I did not consider that I was ever saving in anything but an image using square pixels .
( I also used to run and organise the projecting of images at almost every club meeting for 6 years ) .
My concern is now, that the information I have been able to find online in many instances indicates that 1440x1080 is a video only format ( and therefore not as good or accurate for still images ) in comparison to other standard formats such as these which I do know are used for video also but can be used for photos

* XGA = 1024 x 768 pixels
* WXGA = 1280 x 800 pixels
* HD = 1920 x 1080 pixels
* 4K = 4096 x 2160 resolution
*
When I look at this website the 1440 option does not exist
https://www.projectorpeople.com/reso...tion-guide.asp

The other anomaly is that nobody is able to give me any explanation as to why 1440x1080 was chosen as the projector and laptop used are both capable of 1920 x1080.

1440 x1080 is actually 1.3333:1 whereas 1920x1080 ,16x9 is actually 1.777777778:1
I do understand that PAR or pixel aspect ratio is different to FAR frame aspect ratio

Another site with information on this topic is below
http://www.frankschrader.us/pixel-as...en-format-169/

I hope this is understandable
Cheers
Nick

Based on the hardware. The industry created a standard and that should be uniform, otherwise other problems will be coming up.
Look at your monitor screen. You can change the resolution, but only from a choice the video card gives you.

George

[Manfred M]

Nick - so far as I remember, non-square pixels are a left-over from the non-HD television days when both the PAL and NTSC standards used interleaving to display images. The even line numbers were displayed, then the odd line numbers were displayed, so in effect the blended pixels were effectively rectangular. Some of the early HD video standards, if I remember correctly, used rectangular pixels to deal with transmission and image processing constraints. So far as I know all modern formats use square pixels exclusively.

As for why someone chose the 1440 x 1080 is something you should ask at the club. I suspect it is probably a decision made by someone who thought this would be an acceptable approach. There is currently a discussion at my club of going to a maximum resolution of 1080 x 1080 with the mistaken belief that this will level the playing field for people who shoot in vertical orientation.

The native resolution of actual laptop and desktop screens are dictated by the panel manufacturers and not some specific video standard. I am working on a dual screen desktop and one of my screens has a native resolution of 1680 x 1050 and the other has a resolution of 2560 x 1440.

Forget about non-square pixels; that is a legacy technology.

[Nick100]

Thankyou all for your thoughts and technical insight on this.
Ted I have viewed your photos , I can see what you mean.
Manfred....1080x1080 that sounds like a fun one to deal with
Do I need to mark this as closed or do I let it float in case others wish to participate
Cheers
Nick

[Manfred M]

We only tend to close off threads if they start getting too far off topic. So far this one is providing good, useful information and discussion. Generally threads age gracefully and people stop responding to them and reading them.

If you would like it closed down, please let me or one of the other moderators know and we can do that.

[Nick100]

Thanks .......no let’s leave it go ,maybe others will have some thoughts

[dje]

Forget about non-square pixels; that is a legacy technology.

Nick that is my advice too. Rectangular pixels were only used for standard definition digital video. It's irrelevant to your issue.

Dave