The Mayors Jetty Visit (CLICK TO ENLARGE)
I made some assertions in a couple of workshops that on reflection were truths I had known for such a long time I had forgotten the basis upon which I made those arguments and I was simply telling people that this is the way things are but unable to offer any supporting evidence. I have just run a test on both of these “theories” and here are the findings:
1) Image Compression
I stated that images uploaded to a Wordpress blog should be optimised to 1000 pixels wide and compressed to a 50% (media) ratio. Wordpress compressed images anyway but by reducing the picture first it saves upload time and server load. Wordpress itself will further resize our picture to a choice of 150 pixels wide (thumbnail), 300 pixels wide, or 540 pixels wide. We can present our image in any of these sizes or the original which is 1000 pixels (the one we uploaded) The example to the right shows a picture presented at 300 pixels whilst clicking on it offers up the 1000 pixel wide image.
The question asked was – if we reduce the image to 1000 pixels wide why ALSO perform a compression on it. Well I just ran a test on the image above and created three copies listed below. The file sizes are shown and you’ll see there is a file size saving by reducing the images physical size but by also compressing it there is a futher significant saving with NO DISCERNABLE DEGRADATION of image quality (and therefore optimised for quick web viewing)
- original @ 3456 pixels wide with no compression = file size 4,034 KB view
- resized @ 1000 pixels wide with no compression = file size 483 KB view
- resized @ 1000 pixels wide with 50% compression = file size 78KB view
You can view these images in their various states by clicking the links to the right but it may tale a long while for the original to load. I uploaded these examples via FTP so there is no Wordpress optimisation taking place (“crunching”)
2) Picasa Edits
I stated that tweaks, edits and touch-ups in the free tool Picasa don’t actually affect the image (or video) but just as the way you view it in picasa. I tested this with an image and performed a quite sever crop. I closed down picasa and opened it again and the picture appeared in its severely cropped state. I then closed Picasa browsed to the folder where I knew the image to be and when I opened (viewed) it, the picture appeared in its original un-cropped state. This feature is both useful and anoying depending on what you are trying to achieve. If you want to make your changes permanent you must export a copy. It is in the Picasa export process anyway that the option to resize and compress a picture appears. Emailing the picture sends the editied, in this case, cropped version and not the original.