Suggestions for Images to display on 49' Wide 4K tv screens

[Polar01]

Some of my images are going into a multimedia show that will be displayed on 4 49' wide 4K TV screens. I usually supply images in sRGB 1080px (H) by 1920px (L) resolution set at 100 px/inch, as most screens can only display at 72px. Now the person doing the show is asking from images at double that or 2160 x 3840 now that is only the size not the resolution needed for the screen.
Anyone got a idea of what size and resolution I should send? I have to redo over a hundred images for this show now by Tuesday morning.

Cheers: Allan

[dje]

Allan, I think you are over-complicating things by bringing px/in into the equation. All that really matters is the number of pixels in each direction. The size of the screen will determine the number of pixels per inch but setting this in PS will have no effect on how it is displayed.

If you give them 2160 x 3840, the tv screen will display your images at 100% ie one pixel to one. If you give them normal HD pixel dimensions, the tv will have to upscale to the UHD pixel dimensions. This will still look quite good but probably not as good as using the UHD pixel dimensions in your images to start with.

Dave

[NorthernFocus]

What Dave said. As long as you provide the 2160x3840 image, it will be displayed without any resizing being done by the tv/display. The way you control the sharpening etc. Of course the trick is that unless you have the same resolution monitor to edit/view the images on, you don't know for sure what they are going to look like. At any rate, no need to worry about what your editing software says the image size or px/in is. Just overall pixel dimension to match the display.

[Manfred M]

Sorry for the tardy answer Allan, but with a 10-1/2 hour time difference between where you are and where I am right now...

The real question is do you need to resize at all, and that is the great fallacy about HD displays - unless you are really quite close, you won't actually be able to resolve the difference between a 2K or 4K image. There are a number of arguments out there regarding the arc resolution of where we can indeed detect the improved resolution, but my guess is the saw off point is going to be somewhere between 49" and 98" distance from the screen, after that who cares.

I would probably do what Dave and Dan have suggested and resize the long dimension of your images to 3840 and leave it at that. With Photoshop's image processor function, that is really not that odious a task. As for output sharpening, I would want to check if it is really worth it - i.e. is the difference between what you have now in your saved reference files and what the TV does with them good enough. Don't forget you are still downsampling from your camera's native resolution to 4K, and you will get some inherent sharpening in that operation.

[Polar01]

Thanks Dave, Dan and Manfred, one of the things I have to do is add these to dropbox, I usually size for web 1080 x 1920 at 100dpi/ppi, as my workflow creates files at 360ppi/dpi as I use an Epson printer which likes 360. I live out in the country and the person I am sending to is also in the country the internet speeds are not what I would call fast more like ^&$%!@#%$%^ slow. If I could hand him a flash drive no problem, but internet likely problem, what I am trying is to create the largest but smallest file size that I need to sent over the net.

Cheers: Allan

[Manfred M]

I can relate right now. While I may be in the "high tech" capital of India, Bangalore, the internet here is downright abysmal. I was trying to send a couple of 200 MB files last week and the whole adventure took something like 90 minutes and that included three or four connection drops.

It was even worse the week before, when I was in the remote Ladakh region, when we went for around 5 days in a row with no internet at all. It's a politically sensitive area, close to where India borders on China (Tibet) and Pakistan, so some of the locals were fairly certain that the Indian Army might have cut connectivity for "security reasons".

[Black Pearl]

Completely forget about the ppi as it is meaningless, only the number of pixel along each edge is relevant.

To speed up transfer times increase the compression when you save the file as a jpeg. You won't need the top quality/largest file as any slight compression artefacts won't be visible under any normal viewing distances.

[george013]

Thanks Dave, Dan and Manfred, one of the things I have to do is add these to dropbox, I usually size for web 1080 x 1920 at 100dpi/ppi, as my workflow creates files at 360ppi/dpi as I use an Epson printer which likes 360. I live out in the country and the person I am sending to is also in the country the internet speeds are not what I would call fast more like ^&$%!@#%$%^ slow. If I could hand him a flash drive no problem, but internet likely problem, what I am trying is to create the largest but smallest file size that I need to sent over the net.

Cheers: Allan

As mentioned before, your picture doesn't have a property as dpi/ppi. Your picture has a size in pixels. Those pixels have no physical size. Your output device, screen, monitor, printer, has a resolution as dpi/ppi. When 100dpi they're able to show 100 pixels per inch. This combination gives your picture a physical size.
Size in pixels/resolution in dpi = size in inches.

George

[NorthernFocus]

Robin's advice regarding increasing compression is right on. The only instance where higher compression is likely to show is pixelation in images that contain blue skies or other large areas with very subtle color/tonal variations. But those will likely show up even worse when viewed on a 1080p screen so you can QC the files before sending them and redo them if necessary.

[Dave Humphries]

Another vote for Robin's reply.

Because ppi/dpi is meaningless, most interfaces will remove it if you set the units of size to Pixels, rather than inches or cm

Save your jpgs at no more than Quality 9/12 (= 75%), you could try a lower number/percentage to reduce file size further.