Sharpening for stock photography


When considering the question of should you sharpen images for stock photography websites, the simple answer most libraries will advise, is don't do it.  The rationale behind this is that you never know what size the image is going to be used at and different reproduction sizes need different levels of sharpening. This is more or less along the lines of the larger the image is reproduced the less sharpening is required.

So far so good, however there is a problem. Who exactly in the reproduction chain does this sharpening? Back in film days, designers, picture editors etc. chose their pictures from transparencies or prints and these were sent off to the repro. house for scanning. These companies knew exactly what size to scan at and what levels of sharpening to apply to each image. These days everything is done on screen with desktop publishing packages and the designer presses send and the magazine, brochure, newspaper etc. is sent electronically for printing.

When I ran my own picture library I asked as many people as I could in the reproduction chain whenever I supplied images 'Do you sharpen the image?' I received an almost unanimous 'No'. Consequently having seen some of my images reproduce somewhat soft, I always added whatever sharpening I thought appropriate for the size I was told the image was going to be reproduced at. This is obviously not possible for stock libraries who offer images at different sizes.

So what do I do? Well the larger the image the less I sharpen it. Above are the sizes available from a Nikon D800E file that is currently on sale. As I have written before I have never yet sold a file at the largest size you see above. So I assume that the majority of my sales will be at the smaller sizes, and in fact by far the majority of my images sell at either the medium or large sizes shown above. Just by downsizing from the huge Nikon file means the smaller sizes will look sharper. 

I do pretty much apply some sharpening however to virtually all images I upload, as I'm pretty convinced that nobody else will do it, particularly with images sold via microstock. But its usually less than for the images I post here on the blog. The consequence of this is that because this is where the majority of my images end up, ultimately buying the sharpest lenses isn't neccesarily a priority for me, since if I shoot an image with a super-sharp super expensive lens then I probably won't sharpen it. However if I use a lens that isn't quite so crisp, then I will probably add a little unsharp mask or smart sharpen in Photoshop. In reality the images will probably end up looking much the same on a clients screen.

Now I do, as you know like sharp lenses, who doesn't, but I don't usually buy the seriously expensive top of the range lenses. For my Leica M9 for example I used mostly Voigtlander or Zeiss. I did have a couple of Leica lenses, but one was old and S/H and the other was one of the Leica 'Budget' lenses. (though it did cost close to £1000!!) As you know I'm perfectly happy with my 50mm f/1.8D lens for the D800E and I've just bought the Sigma 12-24mm, which is certainly not the sharpest lens ever made. 

Apart from that its always been my contention that its the sensor and how strongly it is AA filtered that makes the difference. For example I don't think anyone would try to say that the 19mm lens on the Sigma DP1 Merrill is a better or sharper lens than a Leica Super-Elmar-M 18 mm f/ 3.8, but an image shot on the Sigma will look sharper that an image shot with the Leica lens on a Sony NEX-6, simply because of the different sensor and the fact that the Sony has an AA filter and the Sigma doesn't.

Sharpening is a difficult issue, and though the majority of the libraries I supply insist on NO sharpening, I've never once had an image rejected for over-sharpening, even though, as I indicated I do sharpen the majority of images I upload. I have had several rejected for being too soft however. We all make our own decisions as to how much we sharpen our files for viewing on our computers, tablets or if we make prints, but sending files off to websites that can be bought and used for a variety of purposes and in a variety of sizes, things get a bit more complicated. 

When I was shooting weddings, I used to put together digitally printed photo books for the bride and groom and I never sharpened any of the images. Years of running a portrait studio made me learn very quickly that most people are happier with a slightly softer rendition of their features rather than a super sharp rendition of their blemishes, so I thought that to be the best policy. I must say I was always surprised at how well they reproduced. Getty images, the pre-eminent stock photography company always used to insist on no sharpening of digital files, and in fact recommended that images should look 'slightly soft' on the monitor. There are still libraries I supply who insist on this, and I'm always a bit surprised at just what they will accept. More surprisingly is that these are usually the libraries who supply the most prestigious clients and who charge the highest fees for images. It makes sense I guess that the more upmarket the image use, the more care will be taken with appropriate sharpening of the image and in the case of images being used for advertising or for coffee table book publishing, I imagine that someone in the reproduction chain is still looking closely at the images. 

So what would I advise someone who is planning to try selling through picture libraries to do? Well I guess the simplest answer is use common sense. One of the best pieces of advice I could offer to prospective library contributors is don't second guess how your image might get used. For example keep the image as flexible as possible. Have a look at the image downsized from the original. When made smaller does it look oversharpened for example? If so then you have probably applied too much. If its soft at small sizes then you need to apply more.

Preparing images for stock use is different, and requires a slightly different mindset. These days a lot of images are published on the web, but monitoring my sales its obvious that a great deal of mine are still used for print publication. Because of the nature of what I shoot thats probably understandable. Clients buying small images for the web can pretty much see how they are going to look by clicking on a thumbnail, but print is different. There is for example a huge difference in how an image reproduces in a newspaper to how it reproduces in an upmarket magazine. Library images have to be able to handle both, and other possible uses as well. For example I sell a lot of images for e-books these days. 

Finally as with all sharpening, its a good idea to make sure that whatever you apply doesn't result in an increase of luminance noise, though some is perfectly acceptable. Grain still describes it well, even with digital images. However this noise shows up differently in different parts of the image, and bearing that in mind I usually don't sharpen all of an image. For example I never sharpen sky areas, in fact I often slightly soften them. The magic wand tool in Photsohop is very useful for this. However, other denser parts of an image can benefit from more aggressive sharpening and can help give an image a more contrasty look. Particularly useful for images taken in flat light. When we look at our own images one by one, its obviously the best idea to check it out at the size we are going to reproduce it at, however with stock images thats not possible. Even though I've been doing this for years, I do still look at a sample of my images at various sizes, just to check they look OK. Ideally an image should look satisfactory at full-size and its smallest size and if that is the case then I've pretty much got it right.

N.B. to see more on the cameras and lenses featured in this post click on the relevant labels (tags and keywords) below.  

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