The Art of Sharpening | Print Mastery

Perfecting Image Quality for Print: Navigating the Subtle Dance of Pixels and Prints

In the precise field of printing, the process of transforming a digital file into a tangible print is comparable to a well-coordinated routine, where each stage must be precisely managed to ensure a high-quality final product.

A crucial aspect of this process is image sharpening—a key post-processing technique that can significantly influence the print's ultimate look. As we explore the domain of sharpening, we aim to offer insights into how adeptly handling this technique can markedly improve print resolution and image quality, imbuing each print with a touch of professionalism.

Words Jake Hopking
15 Sep 2023
A landscape scene of the Southern Alps and Mount Aoraki, Mt Cook. In the foreground is an array of wildflowers — South Island, New Zealand

Understanding Image Sharpening

At its essence, image sharpening is an optical illusion, a digital sleight of hand that enhances the contrast along the edges within an image, making the details pop and objects appear sharper. This technique is pivotal to counteract the inherent softening effects of digital image capture and the printing process, ensuring that the final print retains a crisp, clear appearance.

A Threefold Approach to Sharpening:
  1. Capture Sharpening: This initial step aims to counterbalance the softening effect from the image capture process, often caused by the camera's anti-aliasing filter and the lens.

  2. Creative Sharpening: A selective process where sharpening and blurring are applied to emphasise or de-emphasize certain areas of the image, guiding the viewer's gaze.

  3. Output Sharpening: The final act before the curtain call, output sharpening compensates for the softening effect of printing, ensuring that the image remains sharp and detailed on paper.

The intricacies involved in these stages highlight the need for a comprehensive understanding of sharpening, making it an indispensable skill for any print aficionado.

The Symphony of Software in Sharpening

The digital age bestows upon us a treasure trove of software tools to fine-tune image sharpening. Tools like Adobe Lightroom and Photoshop, or dedicated sharpening plugins like Nik Sharpener Pro, offer a suite of sharpening features. These software solutions provide presets for output sharpening, taking into account variables like resolution, viewing distance, and paper surface, ensuring each image is finely honed for the print.

Moreover, software like Lightroom eases the output sharpening process by resizing images to the printer's native resolution, preventing the printer from further scaling the image, which could degrade quality. This automation streamlines the sharpening process, ensuring the final print mirrors the sharpness and detail observed on the screen.

Interplay Between Sharpening and Print Resolution
Did you know? Billboards are printed at only 10 dpi! So a 2.8 megapixel (2362 x 1181 px) image can easily be printed at 6m x 3m!

Sharpening and print resolution are entwined in a delicate dance, where each influences the other. A high-resolution image may require less sharpening compared to a low-resolution one. However, the act of sharpening can allow for satisfactory prints even from lower resolution images, particularly when coupled with considerations of viewing distance and software scaling.

An image destined for a large print, viewed from a distance, may not require the same level of initial resolution as one intended for close-up inspection. Sharpening can enhance the perceived resolution and detail, making a significant difference in the print's final appearance.

The paper surface also plays a crucial role in this interplay. A smooth gloss surface may render fine details better, thus requiring a different sharpening approach compared to a rough matte surface, which might mask fine details.

A Pragmatic Approach: Balancing Sharpening and Resolution

A pragmatic approach to sharpening, balanced with the right print resolution, can yield prints that are both visually stunning and sharply detailed. It's about finding that sweet spot where sharpening complements resolution, creating a print that’s not only visually pleasing but also sharply detailed.

Employing specialised sharpening tools, understanding the nuances of print resolution, and considering the viewing distance and paper surface, are all pieces of a complex puzzle. When assembled with care and knowledge, these pieces unveil a beautiful, sharply detailed print that stands as a testament to the nuanced art of printing.

Navigating an A0 Print: A Detailed Exploration

Creating a print of a substantial size such as A0 (841 × 1,189 mm) requires a thorough understanding of resolution, viewing distance, and software sharpening to achieve a polished, sharp output even from seemingly lower resolution files. Let’s illustrate this process through a methodical approach:

Step 1: Initial Resolution

Suppose we start with an image of resolution 3,000 x 2,121 pixels. While this resolution might seem inadequate for a large print, various factors and techniques can significantly improve the output quality.

Step 2: Adjusting to 180 dpi

The common practice is to print at 180 dpi (dots per inch), especially when dealing with large format prints, viewed at increased distances.

The standard practice in the realm of printing often revolves around a resolution of 180 dpi (dots per inch), even though the native resolution of printers typically stands at 300 dpi or 360 dpi, varying with the manufacturer. The adjustment to 180 dpi serves as a general guideline, drawn from a blend of factors including the original resolution, the sharpness of the lens, and the nature of the subject matter at hand.

It's pivotal to recognize that having a higher pixel count is usually advantageous, contributing to the richness and clarity of the printed image. However, in the illustration we're presenting, the emphasis is on demonstrating that even an image with a seemingly low initial resolution — one that might be prematurely dismissed without seasoned insight — can indeed be harnessed to yield an exceptional large format print result. When such an image is printed and showcased as envisioned, with viewers engaging with it from a suitable distance, the outcome can be both impressive and professional. This scenario underscores the potential inherent in images with varying resolutions, and the merit in approaching the process with a nuanced understanding and a seasoned perspective.

The formula to convert pixels to inches is straightforward:
  • Dimension in inches = Dimension in pixels / dpi
For this example image, we get:
  • Width
    3,000 pixels / 180 dpi = 16.7in (424mm)
  • Height
    2,121 pixels​ / 180 dpi = 11.8in (300mm)
Step 3: Adjusting for Viewing Distance

With larger prints such as A0, the viewing distance comes into play. Viewers are likely to stand further back, which compensates for the lower resolution, maintaining the image's apparent sharpness.

Step 4: Software Sharpening

Software sharpening is a valuable tool in enhancing image quality. Utilising software like Adobe Photoshop, the Unsharp Mask or Smart Sharpen feature can be employed to enhance the edges in the image, improving its perceived sharpness. A moderate amount of sharpening can help mitigate the resolution limitation, especially when viewed from an appropriate distance.

The Outcome

Upon applying these steps, the final print, despite originating from a lower resolution file, can exhibit a pleasant level of sharpness and clarity. The combination of adjusting the dpi, considering the viewing distance, and employing software sharpening, facilitates a much-improved print quality. This process showcases how, with a thoughtful approach and the right tools, even a seemingly lower resolution image can be transformed into a striking A0 print, engaging the viewer with its visual appeal and sharpness.

A female horseback archer rides in Yoyogi Park as part of a archery festival — Shibuya, Tokyo, Japan

This image from Japan was shot on a Canon 6D (5,472 × 3,648 pixels) and has more than adequate resolution for A0+ prints!

Delving Into a B0+ Print: A Display of Elkli & Hart’s Precision

At Elkli & Hart, our process of creating original photographic and mixed-media prints begins with capturing high-resolution imagery utilising state-of-the-art cameras such as the Canon 5D MK IV and Canon R5, with resolutions of 6,720 × 4,480 and 8,192 x 5,464 pixels, respectively. These high resolutions play a crucial role in defining the clarity and sharpness of our large B0+ prints, which measure 1,118 × 1580 mm.

Step 1: Initial Resolution

Let’s take an example of an image captured using the Canon R5, which provides a resolution of 8,192 x 5,464 pixels (44.8 effective megapixels). This high resolution is our foundation.

Step 2: Adjusting to 180 dpi

The typical resolution for printing is set at 180 dpi (dots per inch).

As discussed in the previous example, it's important to recognize that printers operate at their native resolution, typically 300 dpi or 360 dpi depending on the manufacturer. This native resolution facilitates capturing the fine details and the subtleties in color transitions, contributing to a high-quality print. However, the guideline of reducing to 180 dpi is explored as a way to demonstrate the flexibility and possibilities in printing, even with seemingly lower resolution images.

In this subsequent example, we're dealing with an input resolution that is quite high. This higher resolution is an asset, as it encapsulates more information and detail, which in turn can be translated into a large format print with a remarkable level of clarity, sharpness, and color accuracy when printed at the printer's native resolution.

The higher the initial resolution, the more data there is to work with, which is especially beneficial when printing in large formats such as B0+. This additional data enables the preservation of fine details, ensuring that the resulting print remains sharp and defined, showcasing the superior quality and professionalism of the print, even at larger sizes. This scenario underscores the value of high-resolution input, particularly when paired with the precision of printing at the native resolution of the printer.

The formula to convert pixels to inches is straightforward:
  • Dimension in inches = Dimension in pixels / dpi
For our image:
  • Width
    8,192 pixels / 180 dpi = 45.5in (1,155mm)
  • Height
    5,464 pixels​ / 180 dpi = 30.4in (772mm)
Step 3: Adjusting for Viewing Distance

A B0+ print has substantial dimensions, and the viewing distance often allows for a lower resolution to still appear sharp to the viewer. The larger viewing distance compensates for the resolution, maintaining a clear and sharp image perception.

Step 4: Software Sharpening

To further enhance the image quality, software sharpening tools are employed. Applications like Adobe Lightroom or Nik Sharpener Pro are used to augment the perceived sharpness by increasing the contrast along edges, thus making the image appear more defined.

In Lightroom, under the Print module, a standard amount of sharpening such as ‘High’ can be selected along with the type of media, like ‘Glossy’. Lightroom then adjusts the sharpening to suit the print size and paper type.

The Outcome

The final step of transferring the sharpened image to print culminates in a B0+ artwork that reflects Elkli & Hart’s commitment to quality. The transition from a high-resolution RAW file to a large-scale print, underpinned by an understanding of resolution, viewing distance, and software sharpening, results in a print that is not only visually appealing but showcases the precision and professionalism inherent in our work. Through this process, we ensure that every print we produce is of a high standard, embodying the fine balance between resolution and print size while embracing the colourful vibrancy inherent in every image.

A Concluding Gaze Towards Quality and Precision

The domain of sharpening offers a detailed insight into how modest digital adjustments can lead to tangible, visually appealing prints. By becoming proficient in sharpening, utilising the appropriate tools, and understanding its relationship with print resolution, one can markedly enhance the quality of prints, ensuring each image is depicted with the sharpness and clarity it merits.

As we delve further into the diverse facets of print mastery, sharpening emerges as a crucial segment in our pursuit of printing excellence, refining not just our images, but our skills and understanding of the nuanced yet impactful art of print precision.

Billboard Magic: A Knowledge-Enhancing Tool for Scaling Imagery

Did you know that billboards, those gigantic canvases that catch our eye on motorways and in public spaces, are printed at a mere 10 dpi (dots per inch)? This low resolution is sufficient due to the viewing distance; the further away you are, the less detail your eyes discern, making a low-resolution image appear clear and sharp from afar.

For instance, a 2.8-megapixel image with dimensions of just 2362 x 1181 pixels can be effortlessly scaled to cover a massive billboard measuring a colossal 6m x 3m. It's a fascinating illustration of how resolution, size, and viewing distance interplay in the world of printing.

Curious about how this scaling magic works? Explore and experiment with image scaling using this interactive Knowledge-Enhancing DPI Calculation Tool. This tool provides a hands-on experience, allowing you to understand the nuances of image resolution and how it translates to print size, especially on a grand scale like billboards.

Print Mastery Series

Continue your education with more guides on the print process.

  1. Optical Brightening Agents
  2. The Art of Giclée Printing
  3. Dye vs. Pigment Inks
  4. The Art of Sharpening
  5. The Science of Colour Accuracy
  6. Paper Essentials in Digital Printing
  7. Dynamic Range in Print
  8. About — Our Materials and Process