Tags: images



Sunday, May 15th, 2022

Image previews with the FileReader API

I added a “notes” section to this website eight years ago. I set it up so that notes could be syndicated to Twitter. Ever since then, that’s the only way I post to Twitter.

A few months later I added photos to my notes. Again, this would get syndicated to Twitter.

Something’s bothered me for a long time though. I initially thought that if I posted a photo, then the accompanying text would serve as a decription of the image. It could effectively act as the alt text for the image, I thought. But in practice it didn’t work out that way. The text was often a commentary on the image, which isn’t the same as a description of the contents.

I needed a way to store alt text for images. To make it more complicated, it was possible for one note to have multiple images. So even though a note was one line in my database, I somehow needed a separate string of text with the description of each image in a single note.

I eventually settled on using the file system instead of the database. The images themselves are stored in separate folders, so I figured I could have an accompanying alt.txt file in each folder.

Take this note from yesterday as an example. Different sizes of the image are stored in the folder /images/uploaded/19077. Here’s a small version of the image and here’s the original. In that same folder is the alt text.

This means I’m reading a file every time I need the alt text instead of reading from a database, which probably isn’t the most performant way of doing it, but it seems to be working okay.

Here’s another example:

In order to add the alt text to the image, I needed to update my posting interface. By default it’s a little textarea, followed by a file upload input, followed by a toggle (a checkbox under the hood) to choose whether or not to syndicate the note to Twitter.

The interface now updates automatically as soon as I use that input type="file" to choose any images for the note. Using the FileReader API, I show a preview of the selected images right after the file input.

Here’s the code if you ever need to do something similar. I’ve abstracted it somewhat in that gist—you should be able to drop it into any page that includes input type="file" accept="image/*" and it will automatically generate the previews.

I was pleasantly surprised at how easy this was. The FileReader API worked just as expected without any gotchas. I think I always assumed that this would be quite complex to do because once upon a time, it was quite complex (or impossible) to do. But now it’s wonderfully straightforward. Story of the web.

My own version of the script does a little bit more; it also generates another little textarea right after each image preview, which is where I write the accompanying alt text.

I’ve also updated my server-side script that handles the syndication to Twitter. I’m using the /media/metadata/create method to provide the alt text. But for some reason it’s not working. I can’t figure out why. I’ll keep working on it.

In the meantime, if you’re looking at an image I’ve posted on Twitter and you’re judging me for its lack of alt text, my apologies. But each tweet of mine includes a link back to the original note on this site and you will most definitely find the alt text for the image there.

Tuesday, April 12th, 2022

Picture perfect images with the modern img element - Stack Overflow Blog

Addy takes a deep dive into making sure your images are performant. There’s a lot to cover here—that’s why I ended up splitting it in two for the responsive design course: one module on responsive images and one on the picture element.

Friday, February 11th, 2022

Awesome astrophotography from the South Downs | Science | The Guardian

To mark the start of the Dark Skies Festival today, here are some fantastic photographics taken not that far from Brighton.

Tuesday, January 4th, 2022

Plus Equals #4, December 2021

In which Rob takes a deep dive into isometric projection and then gets generative with it.

Saturday, December 11th, 2021

More writing on web.dev

Last month I wrote about writing on web.dev. At that time, the first five parts of a fourteen-part course on responsive design had been published. I’m pleased to say that the next five parts are now available. They are:

  1. Typography
  2. Responsive images
  3. The picture element
  4. Icons
  5. Theming

It wasn’t planned, but these five modules feel like they belong together. The first five modules were concerned with layout tools—media queries, flexbox, grid, and even container queries. The latest five modules are about the individual elements of design—type, colour, and images. But those elements are examined through the lens of responsiveness; responsive typography with clamp, responsive colour with prefers-color-scheme, and responsive images with picture and srcset.

The final five modules should be available later this month. In the mean time, I hope you like the first ten modules.

Thursday, September 30th, 2021

Plus Equals #3, September 2021

Want to take a deep dive into tiling images? Like, a really deep dive. Rob has you covered.

Sunday, September 26th, 2021

The Flickr Foundation

A non-profit foundation dedicated to long-term digital preservation.

Imagine if we could place ourselves 100 years into the future and still have access to the billions of photos shared by millions of people on Flickr, one of the best documented, broadest photographic archives on the planet.

The Flickr Foundation represents our commitment to stewarding this digital, cultural treasure to ensure its existence for future generations.

Its first act is the renewal of the Flickr Commons.

Monday, September 20th, 2021

11ty/api-indieweb-avatar: Return an optimized avatar image from a domain name input.

Here’s a nifty little service from Zach: pass in a URL and it returns an image of the site’s icon.

Here’s mine.

Think of it as the indie web alternative to showing Twitter avatars.

Thursday, September 16th, 2021

Basic Pattern Repository

A nice little collection of very simple—and very lightweight—SVGs to use as background patterns.

Tuesday, September 14th, 2021

Accessibility testing

I was doing some accessibility work with a client a little while back. It was mostly giving their site the once-over, highlighting any issues that we could then discuss. It was an audit of sorts.

While I was doing this I started to realise that not all accessibility issues are created equal. I don’t just mean in their severity. I mean that some issues can—and should—be caught early on, while other issues can only be found later.

Take colour contrast. This is something that should be checked before a line of code is written. When designs are being sketched out and then refined in a graphical editor like Figma, that’s the time to check the ratio between background and foreground colours to make sure there’s enough contrast between them. You can catch this kind of thing later on, but by then it’s likely to come with a higher cost—you might have to literally go back to the drawing board. It’s better to find the issue when you’re at the drawing board the first time.

Then there’s the HTML. Most accessibility issues here can be caught before the site goes live. Usually they’re issues of ommission: form fields that don’t have an explicitly associated label element (using the for and id attributes); images that don’t have alt text; pages that don’t have sensible heading levels or landmark regions like main and nav. None of these are particularly onerous to fix and they come with the biggest bang for your buck. If you’ve got sensible forms, sensible headings, alt text on images, and a solid document structure, you’ve already covered the vast majority of accessibility issues with very little overhead. Some of these checks can also be automated: alt text for images; labels for inputs.

Then there’s interactive stuff. If you only use native HTML elements you’re probably in the clear, but chances are you’ve got some bespoke interactivity on your site: a carousel; a mega dropdown for navigation; a tabbed interface. HTML doesn’t give you any of those out of the box so you’d need to make your own using a combination of HTML, CSS, JavaScript and ARIA. There’s plenty of testing you can do before launching—I always ask myself “What would Heydon do?”—but these components really benefit from being tested by real screen reader users.

So if you commission an accessibility audit, you should hope to get feedback that’s mostly in that third category—interactive widgets.

If you get feedback on document structure and other semantic issues with the HTML, you should fix those issues, sure, but you should also see what you can do to stop those issues going live again in the future. Perhaps you can add some steps in the build process. Or maybe it’s more about making sure the devs are aware of these low-hanging fruit. Or perhaps there’s a framework or content management system that’s stopping you from improving your HTML. Then you need to execute a plan for ditching that software.

If you get feedback about colour contrast issues, just fixing the immediate problem isn’t going to address the underlying issue. There’s a process problem, or perhaps a communication issue. In that case, don’t look for a technical solution. A design system, for example, will not magically fix a workflow issue or route around the problem of designers and developers not talking to each other.

When you commission an accessibility audit, you want to make sure you’re getting the most out of it. Don’t squander it on issues that you can catch and fix yourself. Make sure that the bulk of the audit is being spent on the specific issues that are unique to your site.

Wednesday, April 28th, 2021

Earth Restored — Toby Ord

Beautifully restored high-resolution photographs of the Earth taken by Apollo astronauts.

Tuesday, April 6th, 2021

Swipey image grids.

This is how you write up a technique! Cassie takes an SVG pattern she used on the Clearleft “services” page and explains it in step-by-step detail, complete with explanatory animated diagrams.

Tuesday, March 23rd, 2021


Visualising the growth of the internet.

Wednesday, December 2nd, 2020

Creating websites with prefers-reduced-data | Polypane Browser for Developers

There’s no browser support yet but that doesn’t mean we can’t start adding prefers-reduced-data to our media queries today. I like the idea of switching between web fonts and system fonts.

Tuesday, October 13th, 2020

5 most annoying website features I face as a blind person every single day by Holly Tuke

Five pieces of low-hanging fruit:

  • Unlabelled links and buttons
  • No image descriptions
  • Poor use of headings
  • Inaccessible web forms
  • Auto-playing audio and video

Thursday, October 8th, 2020

Full bleed layout using simple CSS | Kilian Valkhof

A follow-up to full-bleed layout post I linked to recently. Here’s how you can get the same effect with using CSS grid.

I like the use of the principle of least power not just in the choice of languages, but within the application of a language.

Tuesday, October 6th, 2020

Same Energy Snap

Match up images that have been posted in pairs to Twitter with the caption “same energy”. This is more fun and addictive than it has any right to be.

Monday, October 5th, 2020

CSS Grid full-bleed layout tutorial · Josh W Comeau

When you’ve got a single centered column but you want something (like an image) to break out and span the full width.

Thursday, October 1st, 2020

AddyOsmani.com - Preload late-discovered Hero images faster

Did you know there’s an imagesrcset attribute you can put on link rel="preload" as="image" (along with an imagesizes attribute)?

I didn’t. (Until Amber pointed this out.)

Thursday, September 24th, 2020

Performance and people

I was helping a client with a bit of a performance audit this week. I really, really enjoy this work. It’s such a nice opportunity to get my hands in the soil of a website, so to speak, and suggest changes that will have a measurable effect on the user’s experience.

Not only is web performance a user experience issue, it may well be the user experience issue. Page speed has a proven demonstrable direct effect on user experience (and revenue and customer satisfaction and whatever other metrics you’re using).

It struck me that there’s a continuum of performance challenges. On one end of the continuum, you’ve got technical issues. These can be solved with technical solutions. On the other end of the continuum, you’ve got human issues. These can be solved with discussions, agreement, empathy, and conversations (often dreaded or awkward).

I think that, as developers, we tend to gravitate towards the technical issues. That’s our safe space. But I suspect that bigger gains can be reaped by tackling the uncomfortable human issues.

This week, for example, I uncovered three performance issues. One was definitely technical. One was definitely human. One was halfway between.

The technical issue was with web fonts. It’s a lot of fun to dive into this aspect of web performance because quite often there’s some low-hanging fruit: a relatively simple technical fix that will boost the performance (or perceived performance) of a website. That might be through resource hints (using link rel=“preload” in the HTML) or adjusting the font loading (using font-display in the CSS) or even nerdier stuff like subsetting.

In this case, the issue was with the file format of the font itself. By switching to woff2, there were significant file size savings. And the great thing is that @font-face rules allow you to specify multiple file formats so you can still support older browsers that can’t handle woff2. A win all ‘round!

The performance issue that was right in the middle of the technical/human continuum was with images. At first glance it looked like a similar issue to the fonts. Some images were being served in the wrong formats. When I say “wrong”, I guess I mean inappropriate. A photographic image, for example, is probably going to best served as a JPG rather than a PNG.

But unlike the fonts, the images weren’t in the direct control of the developers. These images were coming from a Content Management System. And while there’s a certain amount of processing you can do on the server, a human still makes the decision about what file format they’re uploading.

I’ve seen this happen at Clearleft. We launched an event site with lean performant code, but then someone uploaded an image that’s megabytes in size. The solution in that case wasn’t technical. We realised there was a knowledge gap around image file formats—which, let’s face it, is kind of a techy topic that most normal people shouldn’t be expected to know.

But it was extremely gratifying to see that people were genuinely interested in knowing a bit more about choosing the right format for the right image. I was able to provide a few rules of thumb and point to free software for converting images. It empowered those people to feel more confident using the Content Management System.

It was a similar situation with the client site I was looking at this week. Nobody is uploading oversized images in order to deliberately make the site slower. They probably don’t realise the difference that image formats can make. By having a discussion and giving them some pointers, they’ll have more knowledge and the site will be faster. Another win all ‘round!

At the other end of continuum was an issue that wasn’t technical. From a technical point of view, there was just one teeny weeny little script. But that little script is Google Tag Manager which then calls many, many other scripts that are not so teeny weeny. Third party scripts …the bane of web performance!

In retrospect, it seems unbelievable that third-party JavaScript is even possible. I mean, putting arbitrary code—that can then inject even more arbitrary code—onto your website? That seems like a security nightmare!

Remember when I did a countdown of the top four web performance challenges? At the number one spot is other people’s JavaScript.

Now one technical solution would be to remove the Google Tag Manager script. But that’s probably not very practical—you’ll probably just piss off some other department. That said, if you can’t find out which department was responsible for adding the Google Tag Manager script in the first place, it might we well be an option to remove it and then wait and see who complains. If no one notices it’s gone, job done!

More realistically, there’s someone who’s added that Google Tag Manager script for their own valid reasons. You’ll need to talk to them and understand their needs.

Again, as with images uploaded in a Content Management System, they may not be aware of the performance problems caused by third-party scripts. You could try throwing numbers at them, but I think you get better results by telling the story of performance.

Use tools like Request Map Generator to help them visualise the impact that third-party scripts are having. Talk to them. More importantly, listen to them. Find out why those scripts are being requested. What are the outcomes they’re working towards? Can you offer an alternative way of providing the data they need?

I think many of us developers are intimidated or apprehensive about approaching people to have those conversations. But it’s necessary. And in its own way, it can be as rewarding as tinkering with code. If the end result is a faster website, then the work is definitely worth doing—whether it’s technical work or people work.

Personally, I just really enjoy working on anything that will end up improving a website’s performance, and by extension, the user experience. If you fancy working with me on your site, you should get in touch with Clearleft.