Cloudinary Blog

Image opacity manipulation and dynamic watermark generation

Modifying an image opacity so the image is semi-transparent is a common requirement when implementing modern graphics design. Reducing image opacity allows background images to feel less dominant. Reducing opacity also allows layering of multiple images one on top of the other, an important step when adding watermarks, badges and textual overlays to images.
 
Modern web browsers support opacity manipulation via CSS directives. This however does not solve the problem completely. Watermarks need to be embedded as part of the original image and can't be added on the client's side. In addition, manipulating the opacity of the image itself allows for a consistent view across all your service's mediums - website, mobile application, emails (notifications) and PDFs (reports). Emails in particular do not support many of the modern CSS directives.
 
In this blog post we wanted to show how you can use Cloudinary's cloud-based image transformations to easily manipulate the opacity of images and how to use this technique to add watermarks to images.
 

Dynamically changing Image Opacity

Let's look at the following image the was uploaded to the cloud using the 'mountain' public ID.
 
 
You might want to use an image like the one above as a background image for a section of your web or mobile application. Simply set the 'opacity' parameter (or 'o' for URLs) to the desired percentage and Cloudinary will automatically modify the opacity of the image on-the-fly. As always, the resulting image is stored persistently in the cloud  and delivered optimized and cached to your worldwide users through a fast CDN.
 
The following example reduced the mountain image opacity to 20%. Now you can safely place text and other graphical elements above this image.
 
 
 
Below are examples of generating a transformation URL with modified opacity using our client libraries for Rails, PHP, Django and Node.js
<%= cl_image_tag("mountain.jpg", :opacity => 20) %>
<?php echo cl_image_tag("mountain.jpg", array("opacity" => 20)) ?>
import cloudinary
img = cloudinary.CloudinaryImage("mountain.jpg")
img.image(opacity=20)
cloudinary.image("mountain.jpg", { opacity: 20 });
 

Grayed-out Logos

Another common graphic design practice is to display a list of logos of customers and partners in your web site. Instead of the original, colorful logos, many web designers prefer to display semi-transparent grayed versions of these logos so they don't take attention from the website's messaging. 
 
With Cloudinary you can dynamically gray out images, and easily modify them in case your graphic designer has a change of heart.
 
In the following example, we've uploaded multiple logos to Cloudinary. We've went further and used Cloudinary's sprite-generation capabilities to merge these logos into a single sprite image for better performance:
 
 
 
By simply setting the 'effect' parameter (or 'e' for URLs) to 'grayscale' and setting the 'opacity' parameter ('o' for URLs), Cloudinary generates a semi-transparent gray-scale version of the logos for embedding in your website:
 

 

Generating Watermarks

In a previous blog post, we've shown how you can easily add overlays to images. Such overlays could be used to add watermarks to images using a previously uploaded semi-transparent PNG image of such watermark. With the new opacity manipulation transformation, you can upload your non-transparent watermark image and manipulate its opacity dynamically to make it semi-transparent, ready for adding as a watermark overlay.
 
The following example adds the previously uploaded image 'cloudinary_icon' as a 200 pixels wide overlay above the mountain image:
 
 
 
Now, by setting opacity to 40%, the overlay becomes semi transparent:
 
 
 
 
 
You can also apply an effect or filter on the overlay. In the following example we've increased the brightness of the overlay to make it white and reduced opacity to 30%:
 
 
 
The code samples below detail how to build the same URL in Ruby, PHP, Django and Node.js:
 
<%= cl_image_tag("mountain.jpg", :opacity => 30, :effect => "brightness:20", 
                  :width => 200, :overlay => "cloudinary_icon") %>
<?php echo cl_image_tag("mountain.jpg", array("opacity" => 30, 
  "effect" => "brightness:20", "width" => 200, "overlay" => "cloudinary_icon")) ?>
import cloudinary
img = cloudinary.CloudinaryImage("mountain.jpg")
img.image(opacity=30, effect="brightness:20", width=200, overlay="cloudinary_icon")
cloudinary.image("mountain.jpg", 
  { opacity: 30, effect: "brightness:20", width: 200, overlay: "cloudinary_icon" });
 

Summary

Dynamic opacity manipulation and watermark generation are some of the newest Cloudinary capabilities in your image manipulation tool-belt. These capabilities further simplify your web and mobile applications tedious image management tasks. 
 
With a simple URL (or one line of code) you can generate images that match your ever evolving graphic requirements and deliver them quickly to your users. You don't have to deal with complex non-standard CSS directives and you don't have to use over-qualified graphical software like Photoshop to generate images in your desired color balance and opacity.
 
Please share your thoughts and let us know how we can further improve Cloudinary's growing feature set.

Recent Blog Posts

Introducing Website Speed Test: An Image Analysis Tool Integrated with WebPagetest

Because images dominate page weight, methodical image optimization can have a significant effect on conversions and user experience. And the performance tools you choose to use can have a powerful impact on how websites are built and maintained. One such popular open source tool is WebPagetest. It is designed to measure and analyze webpage performance, which is why Cloudinary chose to partner with our friends over there to launch Website Speed Test.

Read more

You might have read some tutorials or articles explaining the importance of images and how to optimize them to deliver a great experience to your users. But does this work really translate into wins for your company? In this talk, you see real-world examples of the positive impact that image optimizations can have on metrics that your bosses and clients care about. You will walk away from this talk with compelling data and useful tools to help you get buy-in and support for this important user experience work at your company.

Read more
Don’t let your digital assets become a liability!

Everyone is a content producer today - from the largest publishing house and entertainment studio, down to the smallest ecommerce store, corporate website or personal blog.

If content is the lifeblood of your website or application, images and videos form the heart that makes it tick and creates an emotional connection with the audience. But, using images and videos to make the content visually engaging and meet your conversion goals, you face a new challenge: managing your digital assets. Because the images and videos are created by different teams for different channels - such as website, social media, ecommerce store, blogs, partners and digital agencies to name a few - chaos can ensue.

Read more

Image Optimization in Python

By Prosper Otemuyiwa
Image Optimization in Python

Approximately 62 percent of today’s internet traffic is made up of images. Media-rich websites must ensure that all images are optimized to speed up the site. A faster site will make your visitors happy; and when they are happy you will likely see increased conversion rates.

Read more