How much to sharpen for screen size (Mac)?

[Richard Stern]

As part of my workflow from raw to saved jpeg images, I generally save the final image as a 2048 x 1365 pxl jpeg on my Macbook Pro 15" retina display laptop. This is usually smaller than the original, so I often sharpen it (the saved jpeg) a little at screen size till it looks just right on my Macbook Pro's 15 in. retina screen, using the sharpening tool in the Adjust Color setion of Preview. If I post it, to, e.g. FB, or on one of the Back Country Gallery forums, or save it in my on line Smugmug gallery, it looks just right on my laptop. But if I view it on a much larger screen, e.g. mirroring it to a large TV, it looks over-sharpened. I'm aware that if an image is downsized it should usually be sharpened a little, but I'm confused, as I don't know what type of screen others will be viewing it.

Here's an example, of a recent image (moderately cropped) that looks fine on my laptop screen but over-sharpened when viewed on a large TV, using an HDMI cble from my laptop. I processed the raw file in LR without sharpening, then used Topaz AI Clear noise removal at 100% view, then added a little Topaz sharpening also at 100% view, saved it back in LR, then cropped it, and saved it as a 2048 x 1365 jpeg in Preview, then sharpened it at screen size a little more.

So should I leave the final jpeg alone and do all my sharpening before saving, or - if not, should I sharpen the final jpeg at screen size or 100%? For those of you looking at this on a large, high quality screen, e.g. a 27" Mac, does it look over-sharpened? Thanks for any advice,

Richard

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[EricBowles]

Realistically - you can't sharpen perfectly for display on all the different screen size and resolution levels. If you sharpen for 4000 pixels on the long side, the image will look soft when viewed at 2000 or 1000 pixels. It's hard enough to decide what to use for different websites because websites will often resize your photo as appropriate for their layout.

Take Facebook for example. Depending on where an image is posted and how many images are posted, it's going to range in size from 1200 pixels to 800 pixels or less. Many of these sites will resize your image automatically if it's too large. Just because you view it on a higher resolution screen does not mean the image is high resolution - and usually it means a smaller resolution image is simple upsized for display. If you want to display the same image on Instagram, Twitter, or here, each site will have it's own optimal size. Sometimes that optimal size is driven by a plug-in or back end software and is not disclosed - and maybe not even known.

Social media image sizes for all networks [September 2024]

The most recent image sizes for different social media networks, including Instagram, X (f.k.a. Twitter), Facebook, LinkedIn, TikTok, and more.

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I normally use 1000 or 1200 pixels on the long side. If I am trying to show detail, I make a screen shot of that detail with 100% magnification.

 

[DRwyoming]

In addition to Eric's comments above, if you know the output display size then sharpen for that use. For instance if the end goal is to display these on a TV monitor or if these will be printed then size and sharpen for that end use. If the idea is to sharpen for general purpose use across a wide variety of display sizes then it's going to be tough but when in doubt it's usually best to err on the under-sharpened side rather than over-sharpened.

 

[bleirer]

There is no exact rule to how much to sharpen, but some considerations. Assuming you sharpened on import, then I think it is best to then do your other editing and save the image as your master, then just before exporting resize it to the web size before sharpening and exporting. I like Bicubic Sharper but Bicubic is also good, in the middle between sharper and smoother. Convert to a smart object to make the sharpening nondestructive. Use unsharp mask or smart sharpen. The radius depends on viewing distance, so small radius for the web, 1 or less. The amount is by eye but based on viewing the smaller image full size. You can use the mask in the smart object if you don't want everything sharpened. Export as a jpeg with convert to srgb and imbed profile checked.

 

[Abinoone]

Can't really add much that hasn't already been written above, except to share what I do, which is to sharpen as little as possible. There's always a temptation to sharpen soft images, but I find that it's very easy to overdo it, which of course gives the image that unnatural look. If my images are softer than they should be and than I'd like, I usually just delete them rather than try to fix them with tools like Topaz AI Sharpen. My rule of thumb is not to sharpen anything more than about 10% or so, max.

You asked about the image you posted above - to me, it looks over sharpened. Sorry.

 

[eaj101]

Personally, I just use defaults on sharpening for screens, change the color space to sRGB, and let it go. You have no control over how your images are seen on the other end. Phone, laptop, TV, high end monitor, twenty year old faded CRT... Of course they're not calibrated either. I make sure the image looks the way I want, especially color balance, and as little sharpening as I can get away with. If I know I'm pushing the image to a platform like Smugmug that pays a little more attention to output, I'll take a little more time. Otherwise it's a big investment of time for little return.

Now, on prints, I'm totally obsessive

 

[BirdDogDad]

Richard, I am looking at your image on a 27" iMac Pro, and yes, it does look a bit over-sharpened. The advice you have received above is right on, I can only add a couple of minor thoughts. In my workflow, I always do sharpening/post processing on the full-sized image, so I know that it looks good at maximum resolution and on a large, hi-res screen. Then I save it as a tiff, keeping the original raw file. If I then need to output a smaller jpeg for online use, I will add some sharpening at that point. It is simply a matter of pixel count--a 100 or 72 dpi jpeg will have less visual information in it, thus the need to artificially enhance it a little more. As mentioned, there is no magic formula--just a happy medium.

With the never-ending quest for "sharpness" among most of us, an oft-overlooked tool that can save many images is the blur tool (I use Photoshop, I assume LR has a similar option). This might sound absurd, but in your shot of the eagle, it is not the eye, the feathers, the body of the bird that makes it look over-sharpened and a bit unnatural--it is the hard outline of the wings. The human eye does not expect to see that, especially on a subject in motion. I have salvaged such images by running a small blur tool carefully along the hard edges, leaving the main subject untouched. It creates a more natural look, especially against a monochromatic background. You might experiment a bit with it--just one more tool to add to the post-processing arsenal.

 

[DavidT]

Interesting subject. I have gotten to the point I don't like to post images on FB for example. It simply looks like crap. It also makes me wonder why so many people chase MP when only sharing online. Maybe Olympus and M4/3 is the future. Why have full frame and high MP and big lenses if non of the detail can be displayed. People seem to be perfectly happy with an iPhone pic.

 

[BirdDogDad]

Interesting subject. I have gotten to the point I don't like to post images on FB for example. It simply looks like crap. It also makes me wonder why so many people chase MP when only sharing online. Maybe Olympus and M4/3 is the future. Why have full frame and high MP and big lenses if non of the detail can be displayed. People seem to be perfectly happy with an iPhone pic.

Much truth to that. I sometimes wonder why I schlep around 20 pounds of very expensive glass and metal when I have a perfectly capable camera in my shirt pocket. Over my career I had no choice but to chase high MP images, since most of my work was for glossy print publication and large trade show displays. For those applications, you can never have enough MP. Probably why I, too, have no interest in posting photos online.

 

[dabhand16]

Years ago when I first started using the NIK collection and it had tutorials on all of the modules and although it was so long ago that I read it IIRC the section on the sharpening module had some really interesting stuff that my memory just can't bring back. Might be worth having a look to see if it is still available.

I made an action based on Steve's two stage sharpening process that produces a web jpg 1600 pixels wide for landscape orientation and another for 1200 tall for portrait orientation. I view my images mainly on my desktop monitor or a laptop and mobile devices occasionally. Never looked at any of my images on a TV but it does not surprise me that you are having issues. When I was heavily into video about 15/20 years ago when you saved your video there were many different writing options depending on what device you were going to view them on.

 

[EricBowles]

When it comes to sharpening, there are a number of issues. It depends a lot on what software you are using to create your output.

Normally there is basic sharpening applied as part of RAW conversion. It could be based on your camera's Picture Control setting, your presets or defaults, or the Profile in Lightroom.

Creative Sharpening is normally applied with a light touch to the entire image, then selectively to specific portions of the image. Noise reduction may be used in a similar manner by applying it locally to backgrounds or similar areas that don't need sharpening. Gaussian Blur is another type of editing that would be applied to reduce noise and create blurred or soft areas. In Lightroom, the settings you use in the Detail panel are also used for local sharpening.

Output sharpening depends on your output size and intended use. Lightroom has preset sharpening levels that consider your output size and sharpen accordingly. Other programs require that you manage output sharpening manually and that takes a little more trial and error.

I remember using Capture NX2 to manually sharpen. For a full size image I had my normal settings that worked. But if I resized for web use, I had to apply sharpening with completely different settings after resizing. The process of downsizing an image requires that sharpening needs to be revisited. Images that use the same settings for sharpening at a full size and a web size can end up looking soft after downsizing.

The final step in sharpening is at the viewer end for digital images. The video driver is going to apply color, brightness, contrast and sharpening settings depending on viewer preferences. If you have oversharpened an image, it's easy to have artifacts show up when it's viewed at a large size.

 

[FB101]

The fact that each person who responded has a slightly different approach is probably a good confirmation that there is no right answer. I try to keep it simple. If I am in PS and I need to downsize for screen, I use one of Steve's handy Actions since he's done all the heavy lifting on figuring out how to get the best output from PS.
If I am in LR - I use the export function, sharpen for screen Normal which works 80% of the time and if I find it too soft I re-export with sharpen to screen High. That's a smart function in LR which takes the output size into consideration and does a decent job at not making a mess of the file.

That's it, but it does assume that I have done a good job at balancing detail recovery and not over-sharpening on the full size file obviously and that can take many forms (Topaz DeNoise or Sharpen, LR highly masked sharpening, high-pass layer technique in PS) depending on file and workflow.