How do you optimize images for high-res displays?

[NZDavid]

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This is related to the obsessing over image quality thread, but I wanted to obsess more about displays. What difference is there and how do you optimize images for different displays?

I really like my new Apple Studio Display — although I also really liked my late-2012 iMac. Pictures are super crisp. But then I had  a problem when I went to resize them for online or email using Graphic Converter as usual — they looked fuzzy. Why? Was I using the wrong settings?

Thorsten from Lemkesoft, who is always super helpful, advised me that it’s all because of the Retina display, which is optimized for 150ppi. The same applies to the latest MacBooks, iPhones, and iPads. I had been saving pictrures at 72ppi (or dpi, as we used to refer to image size in newspaper days). That makes all the difference.

Now the question arises, can you notice? According to Optimizing Images for Retina Displays, “…You probably can’t tell a difference between 2x and 3x, can you? That’s normal. The human eye isn’t capable of perceiving the difference. Much of the recent advances in pixel density are overkill. A hawk could tell the difference; a human, not so much.”

Only, I can tell the difference. Below, a hydrogen-diesel dual-fuel truck, the first one of its kind launched in New Zealand in Invercargill last week. (M10, 2/35-ASPH.) Picture saved at 150ppi but reduced in quality to 92 or it's over 2.4MB and I can't post it. Much better than 72ppi but still not as good as the original. But how sharp it looks will surely depend on the display you're viewing it on.

 

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Edited April 5, 2023 by NZDavid

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[Jeff S]

Already lots of display discussion in the Digital Post Processing section, where you’ll likely get more feedback on your post.

Short story, I stick with a separate NEC or EIZO calibrated monitor, and optimize my files for printing with the aid of ImagePrint software (includes full time soft proofing) and various other workflow considerations. 

A phone camera is generally sufficient for online viewing. I buy all my gear, and optimize my workflow, with printing in mind, not pixel peeping.

Jeff

[marchyman]

On 4/4/2023 at 8:39 PM, NZDavid said:

I had been saving pictrures at 72ppi (or dpi, as we used to refer to image size in newspaper days). That makes all the difference.

Excuse me while I get on my soapbox...  Feel free to totally ignore my rant.

PPI and DPI are functions of the output device.  Nothing you can do in image editing will change the DPI/PPI of the device you are using to output your image.  If you specify an image size in pixels changing PPI/DPI only changes a metadata field in the image.  It does nothing to the pixels that make up the image.   If you set your exported image size to inches or mm the resolution field will be used to calculate the number of pixels required.   That is usually the wrong thing to do when exporting images for a display.

For images to be viewed on computer monitors I specify the desired size in pixels and ignore the "resolution" field.  I tend to use 2K on the long edge as that is not too  big for 2K monitors nor too small for 4K or 5K monitors.  That seems to work OK for general use.  I also export at a 100% quality level and run a post processing program to make jpeg images smaller in file size.  That is handled by my export settings.

[NZDavid]

It’s not so much viewing on your own display that I have an issue with; it’s resizing for print, publishing online, or emailing. Magazines publish at 300dpi and newspapers at 200dpi. The issue is online and email which used to be 72dpi but seems no longer to be the case; it needs to be larger. But you still need to make the image small enough to email. Otherwise, it’s a case of using Dropbox or similar.

[sometimesmaybe]

On 4/7/2023 at 4:38 PM, NZDavid said:

It’s not so much viewing on your own display that I have an issue with; it’s resizing for print, publishing online, or emailing. Magazines publish at 300dpi and newspapers at 200dpi. The issue is online and email which used to be 72dpi but seems no longer to be the case; it needs to be larger. But you still need to make the image small enough to email. Otherwise, it’s a case of using Dropbox or similar.

pls forgive my crude attempt at a summary - are you saying you send your images for publication via email and your images are being auto downsized? 

depending on the size of the image/s (i.e. less than 20mb in total), you can put them in a zip folder and send it that way, otherwise you need to use dropbox, onedrive or google drive etc to share the images without them being downsized etc

[NZDavid]

5 hours ago, sometimesmaybe said:

pls forgive my crude attempt at a summary - are you saying you send your images for publication via email and your images are being auto downsized? 

depending on the size of the image/s (i.e. less than 20mb in total), you can put them in a zip folder and send it that way, otherwise you need to use dropbox, onedrive or google drive etc to share the images without them being downsized etc

Thanks, yes I know that but I was meaning emailing images for publication online not print so they do not need to be such a large file size. The point I was trying to make was that displays such as Apple’s Retina are now such high resolution that the standards have changed and they are best viewed (£and saves) at 150dpi at least and not 72dpi as previously sufficed. Sorry if I wasn’t clear.

[sometimesmaybe]

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3 hours ago, NZDavid said:

Thanks, yes I know that but I was meaning emailing images for publication online not print so they do not need to be such a large file size. The point I was trying to make was that displays such as Apple’s Retina are now such high resolution that the standards have changed and they are best viewed (£and saves) at 150dpi at least and not 72dpi as previously sufficed. Sorry if I wasn’t clear.

oh i see... that was such a poor summary on my part 😅

how good they look will surely be a function of both the display resolution and the original quality of the picture? like how IQ is a combo of the sensor and lens? i'm just guessing without any evidence whatsoever 😬

[NZDavid]

Yes, indeed, as in the film age, there are still many factors at play that determine image quality: lens, recording medium (film or sensor), and display. Then, of course, there's viewing distance and your own perceptions. Objectively, display resolution and overall quality has definitely improved. I'd be keen to know if any others have noticed this and can say whether it makes a big difference to their viewing experience?

  

[sometimesmaybe]

1 hour ago, NZDavid said:

viewing distance

im glad you raised this point, it's something that often gets missed in the discussions.

i often have a chuckle when i read about needing more MP because they want to print 'big'. depending on the specific use case, that might not be needed i.e. think billboard and the viewing distance involved there, it's a big picture, but no one is going to look at it from 30cm away. the digital equiv is looking at an image at 100% / 200% zoom (of course im not saying i don't do that myself 🤓

[jaapv]

On 4/7/2023 at 8:38 AM, NZDavid said:

It’s not so much viewing on your own display that I have an issue with; it’s resizing for print, publishing online, or emailing. Magazines publish at 300dpi and newspapers at 200dpi. The issue is online and email which used to be 72dpi but seems no longer to be the case; it needs to be larger. But you still need to make the image small enough to email. Otherwise, it’s a case of using Dropbox or similar.

If you email a decent pixel number, the user can choose his own DPI setting for the output device. Nothing you do will make a difference, as PPI-DPI is a setting for output devices, not for file saving.

As to 2K vs 4K - I use a 2K editing screen next to a 4K secondary screen. The only difference when looking at the image you posted is that it looks over processed and digital sharp on the 4K screen as opposed to perfectly fine on the 2K screen. When I scale the 4K screen down to 1920 the images are identical. I can imagine that some viewers prefer the 4K look. However, if you make a habit of editing on a 4K or higher screen, you will end up with soft images on print.

[NZDavid]

Thanks Jaap, that makes sense. I'm used to resizing in output quality from newspaper days or for magazines or online, but yes, a decent file size is a good idea. 

I'm having the same issue with trying to resize a pic for the LUF book. It looks OK small but not so good at a larger size. And there's another thing: When I attach it to an email it balloons in size by about 30%. So I have to make it as small as possible.

[jaapv]

The easiest way to get correct resizing is to use the export functions in Lightroom. Other options are to use the native tools of Mac (*) or the DIY system of Photoshop.

I always use command-option-i in Photoshop, only change the pixel number,  and leave everything else at default - including DPI, it is irrelevant ! - and if needed change the compression (quality slider) later in "Save As" 

 

(*) https://www.howtogeek.com/725930/how-to-resize-or-reduce-photo-size-on-mac/