Images are increasingly used in as an integral part of label design to communicate critical information. Their use, therefore, should be bound by the same governance and audit processes as the rest of the label itself.
This guide provides some best practice recommendations on the formatting and management of images in order to maximize the quality and performance of images with label lifecycle management.
1. Using Appropriate Image Types
If saving a simple black & white line or letters image, avoid JPEG as a file type as it is designed to compress color and grayscale continuous-tone images discarding information that the human eye cannot detect.
For example, if this image has the dimensions of 8537 x 7857, and is saved as a JPEG, the resultant file size is 10MB. If the same image is saved as a black and white PNG file, its size is reduced to 120 Kb.
This file size difference will reduce the load on the system in handling the file and manipulating the image.
2. Using Black & White Images
If an image is black & white then the image should not be saved as a color image.
Saving as a black & white (1-bit color depth) image avoids unnecessary image manipulation (dithering) when printing the image to a printer.
When the same image is saved as a color image, and is dithered by a printer, it could result in unexpected results; in this example dotted lines have appeared in the white space.
Saving this as a color image will also unnecessarily increase the file size of the graphic file.
3. Matching Image Dimensions
An image’s dimensions should be reduced to match the intended use of the image:
- If an image is being printed at 1 inch by 1 inch on a label using a 300 DPI (dot per inch) printer, then the image that is ultimately printed will be 300 x 300 dots
- If an image is being printed at 2 inches by 2 inches on a label using a 300 DPI (dot per inch) printer, then the image that is ultimately printed will be 600 x 600 dots
- If an image is being printed at 1 inch by 1 inch on a label using a 1200 DPI printer, then the image that is ultimately printed will be 1200 x 1200 dots
Saving an image, that is intended to be used in any of these sizes /scenarios, as an 8000 x 8000 dots/pixels image does not increase the printed resolution.
It will, however, increase the file size of the image and will require the application or device to manipulate the image at the time of printing.
For example, what may appear to be a modestly-sized JPEG of 397KB can use a large amount of memory when processed by an application.
A 3000 x 3000 resolution image with 24-bit color depth will occupy over 27MB of RAM when uncompressed. If this image is being used to print a small symbol on a label, the image could be reprocessed as a 300x300 PNG image file with 1-bit color depth, providing a size reduction of 99% with no loss of print quality.
Image Reference Guides
To adopt these best practices for image management, it may prove beneficial to create an image reference guide for label and artwork design teams.
The reference guide should provide guidance / rules to follow, such as:
Black and White Images – If the image is black and white then the image color depth should be reduced to 1-bit color and the image should be saved as PNG
Image Dimensions – The image dimensions should be set to meet the dimensions required when printed on a 600 DPI printer (where 600 DPI may be the highest resolution printer in use for production label printing)
Transparency – If an image requires transparency then this should be saved as a PNG file with the transparency color set as magenta
Color Images – Color images should be saved as JPG
It is recommended that guidelines adopted reflect the specific business requirements and operational environments. Having guidelines / rules will allow for consistency and repeatability as well as enabling a level of oversight to be performed easily.
To apply these rules retrospectively to an existing library of images, it is suggested a series of searches will aid review, for example:
- As a first pass check image files that are over a certain size e.g. 3MB
- On the second pass check images that are known to be black and white
- On a third pass check images that are always printed as physically small
Utilizing these image management best practice guidelines will aid in improving label and artwork quality as well as performance and consistency.
*This Best Practice Guide is published and distributed on the basis that PRISYM ID is not responsible for the results of any actions taken by users resulting from the permissions or information contained herein nor for any error in or omission from the use hereof.
About the author
Daniel Green is a Technical Product Manager within PRISYM ID’s Global Products team. His role comprises understanding the functional and technical requirements of life sciences organizations for labeling, and ensuring PRISYM ID’s products are designed to address these effectively. Daniel collaborates with users, customers and partners in order to define and prioritise new features which provide a compelling user experience. Prior to PRISYM ID, Daniel held service and support roles within leading web technology providers.