Set correct date on post

_posts/2016-08-10-the-complete-guide-to-optimising-web-images.markdown

@@ -1,23 +1,23 @@
 ---
 layout: post
 title: "The Complete Guide to Optimising Web Images"
-date: 2016-02-23T11:59:41+00:00
+date: 2016-08-10T13:23:41+00:00
 categories: [web design, images]
 ---
 
 Optimising images for your website can be a bit of a black art, but it's well worth doing as the bandwidth savings can be large. It will also make a big difference to the speed at which your site loads.
 
-#### Why?
+### Why?
 
 These days many of us have access to very fast broadband (we typically have 100Mb/s connections here at thoughtbot) but not everybody has access to this sort of connection. Most people worldwide are still stuck on relatively slow ADSL packages that run at no more than 2Mb/s or so.
 
 Mobile connections have come a long way in recent years, but the variability of speed is even worse than wired connections. 4G can be as fast as good broadband, but in areas with high contention or in areas where there is no 3G or 4G mobile connections can be as slow as mud.
 
-Whatever the speed of the connection it's worth optimising your images as [visitors are far more likely to abandon your site if it takes more than a few seconds to load](https://www.nngroup.com/articles/website-response-times/). It's also worth remembering that even fast broadband connections often have data caps.
+Whatever the speed of the connection it's worth optimising your images as [visitors are far more likely to abandon your site if it takes more than a few seconds to load](https://www.nngroup.com/articles/website-response-times/) and search engines will rank your site higher if it loads quickly. It's also worth remembering that even fast broadband connections often have data caps.
 
 <!-- more -->
 
-#### Size
+### Size
 
 The first thing to do is make sure the pixel dimensions of the image are appropriate. Browsers are much better than they used to be at resizing images as they are rendered, but it is a waste of bandwidth to be sending an image that is bigger than the size that is specified by the markup or CSS.
 
@@ -25,7 +25,7 @@ The context in which the image is displayed should inform the size as well. For
 
 Sometimes it is appropriate to send an image that is bigger than the size it will be rendered. For example, you might have a 2x version of a logo that is intended for HiDPI/Retina displays, and the file size may not be significantly large that it's worth rendering a 1x version as well and adding the complexity needed to deal with swapping the images.
 
-#### Format
+### Format
 
 So you've finished working on your image, and made sure it's the right size. What format do you choose to export it? Well, that depends on the kind of image.
 
@@ -35,7 +35,7 @@ The JPEG file image format was created by the Joint Photographic Experts Group a
 
 The PNG format was designed as a replacement for the then patent-encumbered GIF format. It is a lossless format, able to store images in a variety of colour depths, with either 1 bit or 8 bit alpha transparency. This makes it ideal for storing graphic images with strong lines and flat areas of colour. It is also very good at pristinely storing photographs, but because it's lossless, the resulting file sizes end up being unwieldy for web use so it's better to use JPEG for photos.
 
-#### Optimising JPEG
+### Optimising JPEG
 
 When saving your images for the web it is usually best to use the "Web Export..." feature of your image editor. I'll be using Photoshop in my examples, but most other similar apps have this feature.
 
@@ -46,7 +46,7 @@ When saving your images for the web it is usually best to use the "Web Export...
 
 The main control you need to worry about here is the "Quality" slider. This adjusts the amount of compression applied to the image and will affect the overall quality. Try playing with this control to get a feel for how it affects the final image. You will also see how it affects the file size of the image (shown at the bottom). 65-75% is generally a good starting point, but you may be able to get away with a lower value for certain kinds of image. Conversely you may have to set it higher to get a result you are happy with. Use your judgement here.
 
-#### Optimising PNG
+### Optimising PNG
 
 There's a bit more to think about when saving a PNG file. PNG files can store images in a variety of [colour depths](https://en.wikipedia.org/wiki/Color_depth) and with 1-bit transparency or an 8-bit [alpha channel](https://en.wikipedia.org/wiki/Alpha_compositing).
 
@@ -69,6 +69,8 @@ If you are running Windows you can try [FileOptimizer](http://nikkhokkho.sourcef
 
 Happy optimising!
 
+*This post was also published to the [thoughtbot blog](https://robots.thoughtbot.com/the-complete-guide-to-optimising-web-images).*
+
 *[ADSL]: Asymmetric Digital Subscriber Line
 *[JPEG]: Joint Photographic Expert Group
 *[GIF]: Graphics Interchange Format