I’m Michael, long time reader, first time poster. As part of the StreetAdvisor development team I’ve focused mainly on the media processing side of things including the photo and video processing.
You may have noticed that as part of the latest release the photos on StreetAdvisor are looking a lot better than before. I’d hate to disappoint you but that’s not just your new fancy LCD monitor but a total rework of the image processing that goes on behind the scenes. Three main features have been added or improved in this release.
High quality JPEG processing
This was the largest piece of work and required a total rewrite of how we handle the photos you upload. In the past the images were resized for display in StreetAdvisor using a quick and nasty method which removes pixels with total disregard for their neighbors. The new resize uses a method that software like Photoshop incorporates, namely ‘bicubic interpolation’.
This method looks at which pixels are surrounding the pixel(s) being removed and smoothes the image out to produce a result closer to the original image. Take a look at these samples where the ‘jaggies’ from the old photos are totally gone or at the very least minimized.
Australia before and after
All the resized images are now saved at 90% JPEG quality making the average file larger than in the past but they look a lot better due to a lack of compression artifacts.
UK before and after
USA before and after
USA before and after
Intelligent thumbnail processing
Similar to the method employed to resize images previously was the method to produce the little thumbnail images you see on StreetAdvisor. Previously the image was stretched to fit the standard thumbnail size (88x66 pixels if anyone is interested) which, if you had an image that was exceptionally wide or tall, would look rather odd.
Now, instead of stretching the image it is scaled down to fit the lesser of its dimensions (height/width) then the overhanging pixels are chopped (cropped) off. You can see in the following example how this portrait format photo was stretched out wide in the old thumbnail and how in the new one the top and bottom are cropped. This method gives you a better idea of what the larger format image looks like as the aspect ratio remains intact.
Australia before and after
IPTC IIM meta data persistence
When you take a photo with your digital camera information relating to which camera you’re using, what lens you have attached to it and other settings from your camera are stored in the photo. In JPEGs this data is known as the IPTC Information Interchange Model and in the past was dropped from the resized images. This data is now copied over from the original image to the resized image on StreetAdvisor for future use. Here is an example of a photo’s IPTC IIM data.
A little side note here, other image formats use EXIF data which is very similar to IPTC IIM but as with most standards, there are plenty to choose from.
If all that was as clear as mud, I apologize, just know that all the photos on StreetAdvisor now look much better. All existing photos on StreetAdvisor have been reprocessed using these new techniques and any new photos uploaded will of course run through them too.
I hope you enjoy the improvement in quality and I will be keeping an eye out for all your new photos hitting the site.
Michael Soutar
Media Tech Guy











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