Exercise 24: Sharpening for Print

Do we actually sharpen an image? To my understanding we are just creating an illusion. There are various terms used for this process, e.g. sharpening the image, unsharp mask etc. Understanding the traditional method (pre digital) of sharpening helps in grasping the concept better. The technique was first used in Germany in the 1930s as a way of increasing the acuteness, or apparent sharpness, of photographic images.…… Retrieved from http://en.wikipedia.org/wiki/Unsharp_masking  (Accessed on 15/05/2012). Certainly digital invention has made photography fairly adaptable, and at the same time quite complicated. No doubt editing process and the costs have become more and more accessible than earlier. However, the variety of media challenges the editing abilities. It is very important that images are appropriately sharpened for the medium of display. The images can be displayed on a wall with a projector, presented on a website, accessed through a smart phone or iPad like devises, or can be printed. Again print medium and size also vary from a postcard to a wall-to-wall advert. Most of the photographers use the sharpening technique to enhance the images, unless they are specifically looking for a blurry effect.

This exercise requires me to experiment with varied degrees of sharpening, and then compare the prints with the on screen appearance. This will surely help me to understand the required amount of sharpening for the print medium. Parallel to this, I also plan to observe the onscreen effects of sharpening. This is especially required as prominence on digital media is evident.

I prefer using Lightroom, when it comes to managing the workflow or basic images editing/processing. I do use “Edit in Photoshop” option for the images requiring Photoshop treatment. However, eventually all images are exported through LR 3. Hence, I would concentrate on the sharpening process used in LR 3. The link below explains the process of using the unsharp mask in Photoshop precisely http://digital-photography-school.com/an-introduction-to-sharpening-photos  (accessed on 15/5/2012).

Normally, I shoot in RAW format and keep the “in camera sharpening” option set to “Off”. This gives me flexibility to get desired effect of sharpening. LR does not over-right the image file, instead stores the processing information separately. Hence, reverting the sharpening effects in LR is very easy and does not affect the original image.

Sharpening stages:

One can influence sharpening at 2 stages in LR. Stage one: after importing the images, as a part of processing. Second stage: at the time of export. Let us look at both the stages. It is important to know that over sharpening can introduce imperfections like noise, visible lines, zigzag lines, and too much texture in an image.

Stage One

After importing an image, we can sharpen the image within the “Develop” module. Under the “Details” tab there are four sliders, which enable us to make these adjustments.

Screen-shot_Details Amount Slider: This slider allows regulating amount of sharpening; setting the value to 0 can turn off the sharpening. Depending on the amount specified, the contrast between varying pixels increases. This creates the illusion of the edges being sharpened.
Radius: Regulates the area to which sharpening is applied (outside the perceived edge). It is like the feather effect of “Photoshop”. Need to use this slider judiciously; otherwise it can produce strange effect.
Detail: This slider adjusts how much sharpening will be applied on the details of the image. Smaller number will be restricted towards the edge, where as a higher number will affect greater details. This slider can help to bring out the texture. However, there is a risk of increasing the noise in an image.
Masking : This is the most practical and nifty feature. It masks the area that does not require sharpening. It is similar to the mask tool in Photoshop however; it is not as controlled.

Stage Two:

The second stage sharpening can be applied at the time of exporting.

Screen-Shot-Export

The options are defined as follows (taken from the LR help):

You can apply an adaptive output-sharpening algorithm to your JPEG, PSD, a TIFF photos when you export. The amount of sharpening that Lightroom applies is based on the output media and resolution you specify. Output sharpening is performed in addition to any sharpening you apply in the Develop module.

  1. Select the Sharpen For box in the Output Sharpening area of the Export dialog box.
  2. Specify whether you are exporting for Screen, Matte Paper, or Glossy Paper output.
  1. Change the Amount pop-up menu to Low or High to decrease or increase the amount of sharpening applied. In most cases, you can leave the Amount set to the default option, Standard.

For more details please refer to the link http://help.adobe.com/en_US/Lightroom/3.0/Using/WS75C39DDC-B701-4840-A703-0755A5C04878.html#WS2bacbdf8d487e582-244c8e7b131dee359a4-7ffc (accessed on 15/5/2012)

Process description  

I have chosen an image from my archives to demonstrate the sharpening process. After importing the images and making some basic adjustments, I made 3 virtual copies of the image. After that I have applied the following sharpening process.

Original Image:

Ex-24-1

1. Original Image:

I started with the following image. LR applies default sharpening to all the imported images. Default sharpening values are: Amount – 25, Radius – 1.0, Details – 25, Masking – 0

Screen-Shot-Orginal

2. Virtual copy one:

As the exercise brief suggest, I applied sharpening. This was the image with least sharpening, and the changes were quite similar to the original image.  Before = original, After = Sharpened. Amount – 35, Radius – 1.0, Details – 25, Masking – 0

Screen-Shot-sharpen-35

3. Virtual copy two:

Still at this stage the image has not been affected dramatically, and when zoomed out looks pretty okay.  Before = original, After = Sharpened. Amount – 100, Radius – 1.0, Details – 53, Masking – 0

Screen-Shot-sharpen-100

4. Virtual copy three:

Now the image has lot of noise and other noticeable flaws. Masking the area will bring down the severity of the sharpness. However, to demonstrate the effects of over sharpening, I have refrained from using the masking slider.     Before = Original, After = Sharpened. Amount – 150, Radius – 1.0, Details – 25, Masking  – 0

Screen-Shot-sharpen-150

Note: in the screen shots above the difference is not so visible. However, on my screen the image looks damaged due to over processing.

I often use option/alt key while moving the sliders this shows the areas being worked on. See the image below; all the areas in grey and white colour are getting sharpened. This screen shot is taken while the alt key was pressed, and the masking slider was being adjusted.

Screen-Shot-sharpen-alt

This video on YouTube sums up the process I follow during sharpening the images. http://youtu.be/p0b9hB-lVOk (Accessed on 16/5/2012).

Normally, I do not print photos at home. Instead, I prefer using specialized printer for my large or canvas prints. For normal size matt finish photographs, I outsource the work to a local vender.

After printing the images, I observed them with a magnifying glass. Comparing the prints against 100% magnification on the screen reveled that the prints were more tolerant to sharpening. Prints did not show any imperfections on the first 3 variations of sharpening (till amount=100). However, variation 3 on the screen had visible flaws. On the screen, last variation of sharpening was totally unacceptable. It had noise and abrasions. Compared to that, printed image was slightly better. Must note that the print sizes were small. Hence, probably it had absorbed many flaws. I am sure it will be more noticeable on larger prints.

Conclusion:

Sharpening the image surely gives better definitions to most of the photograph. However, it is very important to understand that it cannot fix a photograph that is originally blurred or out of focus. In fact over sharpening actually damages the image and introduces unwanted imperfections.

Earlier for some of the images, I used to go bit aggressive on sharpening. However, when my tutor pointed out the problem during the assignment 1, I researched the topic and understood the importance of using the correct amount of sharpening. This exercise reinforces the prior learning. Now, mostly I use the default sharpening, and adjust it further only if required. Eventually I would like to look at the commercial aspect of the photography. Hence, it is important that I stick to the standard industry practices. The stock libraries discourage sharpening, as normally clients want the flexibility of sharpening the images as per their requirements. It is easy to sharpen an image. However, it is quite difficult to undo the sharpening effect. Thus, it makes sense leaving the sharpening to none or minimum.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: