Why have SVG images not yet replaced PNG on the web?

http://blog.sekera.cz/2013/09/why-svg-images-did-not-replace-png.html

by seky • 13 years ago

76 111 13 years ago

blog.sekera.cz

ris2• 13 years ago

Answer: because there are plenty of things you simply can't express in SVG with its current level of support across browsers.

e.g. no blend mode except "normal" really works reliably across browsers yet. And just a reminder: it's 2013, everyone.

Next question...

andrewmunsell• 13 years ago

Pretty much exactly this-- advanced stuff only express-able in Bitmap format (such as photos, complex patterns, blending modes, etc) cannot be represented in SVG. That is, unless you use a Bitmap embedded in the SVG, but then what's the point? It's just simpler to use a bitmap format right now.

seky5• 13 years ago

Well, many websites uses simple graphics, simple logos... It's 2013 - yes, and nowadays simple, flat, design is modern, rather than graphics with a lot of effects, that was modern in the past, IMHO.

But I agree with your argument regarding to something is not properly - yes, that can be the reason why people don't see the whole thing as reliable

corresation2• 13 years ago

no blend mode except "normal" really works reliably across browsers yet

Compared to what? What alternative does reliably have blend?

ris2• 13 years ago

There isn't one (except I'm sure someone's going to pop up here and say flash).

So the only alternative is something that's been pre-composited down to pixels for you, probably in a png.

qwerty_asdf• 13 years ago

Because parsing XML can become a bottomless pit of nightmares and sorrow. Unholy floating point calculations that make Baby Jesus cry.

Meanwhile, pixel rasters are a finite array of bytes, confined to specific dimensions and resolutions. Plain old integers in 24 bit color with an 8 bit transparency channel.

And, specifically with respect to PNG, those pixel values are compressed row-by-row, using the DEFLATE algorithm.

MaxGabriel• 13 years ago

Re: the author's experience with Android: Android 2.x doesn't support SVG. It makes up 33% of the devices that visit the Google Play store

http://caniuse.com/#cats=SVG

http://developer.android.com/about/dashboards/index.html

droidist2• 13 years ago

True. Android is the new IE when it comes to supporting features like this. Strange since Google pushes HTML 5 so much.

oofabz• 13 years ago

A vector format is insufficient to make an image look good at all resolutions. Without hinting, lines are not aligned to pixels, making them blurry.

We have solved this problem with fonts, but it is extremely complex, both for the artist and for the rendering code.

terabytest2• 13 years ago

Not entirely true. A lot of times resolutions are just double the normal one, so the SVG image scales perfectly and looks good.

seky5• 13 years ago

I have written my prev reply before I've seen yours.

Yes, if its mostly double-sized resolution then blurring shouldnt be a prob,

And when it is some strange "1.something" or "2.something" resolution, then probably also PNGs will look blurred, unles you dont supply exact special PNGs for such resolutions

tghw• 13 years ago

Assuming it was hinted to the intended resolution. But that's still an extra step.

seky5• 13 years ago

I see, it is an interesting point, thanks.

For me, that would be one of the main reasons against SVG

bronson• 13 years ago

Except that all other image formats suffer the exact same problem. Some filters may be better tuned for different image types but there's no good, generic solution. Avoiding SVG doesn't solve this at all.

tobr• 13 years ago

This is true, but it's still much better than pixelated blur or aliasing. Also, most of the time you have the same problem when authoring a bitmap with vector tools too, unless you very carefully target a specific output resolution. If you really need pixel precision you can always use bitmaps, but vector is perfectly fine in many/most cases.

I wonder though - would it be possible to apply hinting to svg with javascript?

Pxtl4• 13 years ago

Except we have the reverse problem with raster images now that we have devices with vastly different DPI. An iPad 3 has like 4X the DPI of a 30" screen. If you want them to be displayed at a reasonable size on both devices? You've got a problem.

If we start seeing 4K screens, worrying about those blurry anti-aliasing lines is going to seem absurd.

morley• 13 years ago

So the question is whether to (1) make the experience worse for people with high-DPI devices, (2) make the experience worse for everyone, or (3) make one bitmap for one market and another, larger bitmap for the other market. I'd imagine that most web projects have a vast majority of users on "normal" DPIs, so the best options would be (2) or (3).

JohnHaugeland2• 13 years ago

I have several screens in this DPI range. Actually, at 4k 30", your phone is probably in this range.

Use your phone to contrast AA to non-AA. The difference is still pretty enormous in my opinion.

sambeau4• 13 years ago

Retina displays are removing the need to worry about this. When pixels are invisible, hinting problems are invisible too.

masklinn5• 13 years ago

They don't, hinting is also about removing details which you can't do in SVG.

When people provide icons in many physical sizes, the icons generally aren't mere scaling up and down, because even if you can hint so the lines themselves don't blur the details will get so small the whole icon becomes a mess. Apple even has a note on this in their HIG:

If an icon’s content or shape is overly complex, the details can become confusing and may appear blurry at smaller sizes.

note that this is not about logical size and retina displays, it's about physical size and the viewer's eye's power of resolution.

mark-r• 13 years ago

You may not be able to make it look good at all resolutions, but it's often adequate to make it look good at some minimum and anything above. You can do that without hinting.

crazygringo2• 13 years ago

Optimizing for hinting has been rendered pointless by the fact that people zoom around on mobile devices.

You can no longer expect bitmap pixels to map to device pixels in any reasonable way. (Heck, just turn your desktop browser zoom to 90% or 110%.)

There was a time for hinting, but it's long gone.

seky5• 13 years ago

Not to say, if you (easily on such devices) zoom to max zoom on a hi-res display, the resulting image is 8times zoomed in comparison to normal desktop PC image. And for same quality (sharpness), you wouldn't only need 8times larger PNG for this, but 8x8=64times larger PNG.

mistercow3• 13 years ago

I don't understand what exactly zooming has to do with hinting. Fonts use hinting to great effect, and they're specifically designed to be displayed at different sizes and resolutions.

mistercow3• 13 years ago

Also, basic hinting is not terribly difficult for the artist with modern font design tools. Similar tools could be provided for SVG hinting. Also, auto-hinting works pretty well. I have often wondered why there has been no effort to do the same thing with SVG renderers. At the very least, they could be rendered at 2X and then downsampled with a lanczos filter. The effect is not the same, but it's far from orthogonal.

But is hinting even possible in a format that supports multiple colors? It does not seem obvious to me that it is.

thisrod• 13 years ago

A generation ago, paper had the kind of resolution that screens do now, and all the problems mentioned in this thread came up when books were printed. This made them problems for Donald Knuth. He tackled them with his usual genius, and the result, MetaFont, has been free software ever since. I've always thought a time would come to embed it in web browsers; it sounds like now might be that time.

bcrescimanno• 13 years ago

Let's not forget the issue that scaling vectors does not necessarily mean scaling intent and communication. Vector imagery for some things sounds great; in practice, it doesn't always come out as well as you'd hope--and certainly not as well as a hand-optimized set of work.

See: http://www.pushing-pixels.org/2011/11/04/about-those-vector-...

deletes• 13 years ago

>as PNGs are just plain bitmaps<< .png is definitely not a plain bitmap.

http://en.wikipedia.org/wiki/Portable_Network_Graphics#Compr...

etchalon2• 13 years ago

Exporting a bitmap is easy, and will always look correct when rendered.

Exporting SVG is difficult, requires specific tools, and is gonna render differently depending on the browser.

SVG solved a problem exactly no one had.

Mindless2112• 13 years ago

SVG solved a problem essentially everyone will have: pixel density.

masklinn5• 13 years ago

Except it failed to solve the related problem which everybody already has: eye resolution.

amadeus• 13 years ago

I'm surprised file size hasn't been mentioned as a mother major reason.

With tools like ImageOptim, and ImageAlpha, you can make PNGs INSANELY small with 0 or an imperceptible loss in quality.

For example, PNGs do insanely well when you have few numbers of colors that are repeating often. I've had had images that were 640px by 960px (pixel style art) that compressed down to sub 3kb with no quality loss. Good luck getting that with an SVG.

(Yes, there are certain types of images that PNGs are a terrible solution for, however, really, what I mean here is, right tool for the job.)

dmlorenzetti• 13 years ago

I used SVG to make some interactive demos of some methods for solving ordinary differential equations. At the time, I remember being frustrated by the poor documentation available for the scripting aspects.

Naturally, there are a number of web resources, but none of them felt authoritative (in the sense of complete coverage). Furthermore, they used different techniques, so it was hard to integrate code samples from different sources. Finally, some had outright errors (my vague memory is that some of this was due to the documentation being written before a working implementation was available).

All of this had the effect of making me feel like SVG was a bit of a backwater. I liked the technology, and was willing to use it since I had total control of the machine I was going to run the demo on. However, I didn't feel comfortable with the idea that I could make the demos public and have them run anywhere.

drcode• 13 years ago

I think SVGs have failed so far on the web because of a sort of "paradox of choice": As soon as you use SVG images, you'll be tempted to make them do things you can't do with PNGs, but you still end up in a world of hurt if you attempt to do this.

Chiefly among these new features are (1) inlining directly into html (2) making them interactive via javascript.

Both #1 and #2 are possible in theory, but in my experience these features are very painful practice... both of these are still very buggy. That's the problem with SVGs: Most of the new "options" they open up are still not ready for prime time.

corresation2• 13 years ago

Most of the new "options" they open up are still not ready for prime time.

I had an article in MSDN Magazine promoting SVG graphics 10 friggin' years ago, and it made use of inline SVG and JavaScript animations, to fantastic effect. Since then I've used SVG in countless places, with very little downside. The major problem are some laggard browsers, but if you have a supporting browser neither inlining and script are a problem whatsoever.

SVG is one of those technologies where many (such as myself) overestimated the short-term impact, and under-estimated the long term impact. As a technology it was usable and enormously powerful in some situations ten years ago, but it is really just starting to gain serious inertia.

ygra3• 13 years ago

I guess Wikipedia's approach is a fairly good one here: Use SVG behind the scenes and generate PNGs for the articles themselves in the necessary sizes. Fast display of PNGs (also for complex imagery they tend to be smaller, but that's often just because Inkscape's default SVGs are horribly bloated¹) and the vector image for easy changes and printing.

That being said, back then I struggled fairly often with annoying bugs in Wikimedia's backend renderer rsvg. It got better over time but back then browser support was also very spotty. By now SVG is still my favorite vector format to use, mainly because it's trivial to write scripts around (it's just XML after all) and converting to PNG if you need it (or whatever else is needed) is trivial.²

So generally I'd say SVG is very much not dead, it's just rarely used directly on the web, except for interactive things where hit-testing arbitrary shapes is important.

____

¹ I used to vectorize a few (around 200–300, I think) flags on Wikimedia Commons and for simple shapes I concentrated on it was usually a difference of 350 bytes vs. 2–3 KiB. I wrote my code by hand for the most part, utilizing a few templates for common flag formats (n horizontal or vertical stripes, checkerboard, etc.) and small scripts for the more annoying things to write by hand, like wavy lines.

² Current use case from today: action bar icons on Android. When creating them in Eclipse from an image it only generates enabled, not disabled icons and I have to remember what padding I used and select the correct theme. After two or three changes in the source images (which were SVG anyway) it was enough and I just wrote a tiny script to generate them. Another use case were the images in my final thesis which I kept in SVG because back then I wasn't sure yet whether to use Word (needs EMF) or LaTeX (needs PDF) for writing. The fact that I needed Graphviz a lot which outputs nice, clean SVG also helped.

marijn2• 13 years ago

The responses here (so far) are mostly pointing out why SVG is not suitable for all situations. There are many images where

- SVG will be smaller than a bitmap

- The sub-pixel rendering isn't really an issue (do you check that all the lines are aligned on pixels when you export something from illustrator?)

- No advanced/poorly supported features are necessary

Platform support is still a stumbling block, but that will get better. I seriously considered going svg-only for the vector-friendly illustrations in the new edition of http://eloquentjavascript.net . But in order to not screw over people on old devices, I will probably use svg with png fallbacks instead.

guptaneil• 13 years ago

Honest question: Will people with devices old enough to not be able to render svg really be reading a programming book?

marijn2• 13 years ago

Well, my own phone is unable to render svg, so I can imagine there is such an audience.

hack37• 13 years ago

Being a programmer doesn't mean living with the latest gadget.

crazygringo2• 13 years ago

For some time, all major browsers already support SVG.

Not time enough. Plenty of people still use IE8, which doesn't.

frik• 13 years ago

You can use SVGWeb as fallback solution for IE6-8 user: http://code.google.com/p/svgweb/

panzi2• 13 years ago

If your SVG file is properly crafted (viewBox & maybe preserveAspectRatio attributes) then you can do this:

    <object type="image/svg+xml" width="640" height="480" data="http://example.com/image.svg">
        <img src="http://example.com/image.png"/>
    </object>

puller• 13 years ago

Because browser support is inconsistent, SVGs are often larger than equivalent than even lightly optimized PNGs, and it's a lot easier to find or create raster images than to obtain high-quality vector art. Also, you actually often want different images at different scales, so that automatically scaling one image is not that big an advantage.

I want to use SVG, particularly in Javascript apps. It seems like a more elegant solution/workflow for things like icons. It would certainly beat abusing fonts to put small images on a page. but it has sort of missed its opportunity.

sambeau4• 13 years ago

I use SVG a lot and I'd say the reasons are:

* Browser support is still new and in places still a little rough

* IE support has only recently arrived

* SVG creation tools are either rough or expensive

* SVG can create sub-Flash-like performance if used carelessly

* SVG has no detail optimisation (or detail hinting)

I think we're about to see SVG usage pick-up steam now that IE has support and retina displays are becoming commonplace. Hopefully we'll get the tools and performance we deserve.

I'm very hopeful for SVG in the next 18 months.

gglanzani• 13 years ago

[Not trolling, genuinely interested in the answer]

* SVG can creat sub-Flash-like performance if used carelessly

Could you elaborate on that? What should I be aware of if exporting vector art from, say, Illustrator or Inkscape?

ygra3• 13 years ago

From Inkscape? Little, as SVG is its native format and thus Inkscape's feature set aligns nicely with the capabilities of the format (if used carefully, e.g. using clones instead of copies for identical shapes, etc.). Illustrator, however, will export more or less with a minimum SVG feature set used and for complex drawings that may end up fairly large and fairly inefficient.

Drop shadows and filters in general are a concern. Not so much on desktop browsers nowadays, but in mobile very much.

sambeau4• 13 years ago

iOS performance is generally awful with SVG. Scrolling used to be bad but I think Webkit fixed that bug.

Too much detail has been the cause of the worst performance (and crashing) I've seen — one image of a playing card froze my iPad.

http://code.google.com/p/vectorized-playing-cards/

try this guy: http://www.totalnonsense.com/misc_images/Jack_of_Spades_vect...

Blurs can be slow on large images.

Drawing Big SVGs can be problematic too.

Grue32• 13 years ago

Just open any SVG map from Wikipedia at full resolution... Guaranteed browser hang.

ronaldx• 13 years ago

Also PNG file size is typically smaller than SVG size unless you are literally drawing Bezier curves.

sliverstorm2• 13 years ago

SVG can create sub-Flash-like performance if used carelessly

Perfect. You just know that it will be used carelessly, too. Some of my low-powered devices are already stumbling under the concept of a "modern" website (which seems to revolve mainly around using as much js as can possibly fit onscreen), I'm not looking forward to widespread adoption of this next piece of "progress".

mapt• 13 years ago

Last I tried to use an SVG workflow during a stint working for Wikipedia's Map Workshop three years ago, Inkscape broke in subtle ways every other map it had to open, and Illustrator had near-zero chance of successfully rendering an SVG map created somewhere else even moderately close to the desired appearance, and only 75% chance of correctly rendering an SVG map exported from itself five seconds earlier. They both have some ugly filesize bloat in the way they handle styles.

On top of this was Wikipedia's use of an SVG->PNG renderer that is openly acknowledged to render worse than its competitors (which were not great), for better performance.

Until there's a reference implementation of SVG... a real spec with an exhaustive ACID-style test on every single feature... I won't revisit trying to work in it.

taf2• 13 years ago

We use SVG on our homepage via raphaeljs to draw the graphics showing marketing, phone calls, metrics, and insights... It was always my goal to one day animate it to help better explain our product, but for now I think it looks pretty good and the PNG version was larger in bytes when converted... the example is here: https://calltrackingmetrics.com/features

anjc• 13 years ago

Because they're completely different formats to be used for completely different purposes?

neovive• 13 years ago

The SVG spec has been around for so long, but the fact that it competed directly with SWF held it back. Adobe was a major proponent of SVG until they bought Flash and focused their efforts accordingly.

Although SVG is "readable" in a text editor, all but the simplest shapes are extremely complex and require the use of graphics editors such as Inkscape. Vector formats are definitely the future for source images as they can generate any size bitmap you need for any device. However, as a delivery format, SVG will likely be relegated to niche and specialized sites (e.g. data visualizations and animations) for quite a while.

ScotterC• 13 years ago

I would say the main reason is because there's not a 'Save As SVG' in photoshop. Most non tech people haven't heard of SVG and by the time they have, they already have a process for making images and the switch doesn't have enough apparent value on the surface.

Pxtl4• 13 years ago

Also, illustrator sucks.

nness• 13 years ago

Illustrator is an absolutely fantastic tool for print production and design. It is not a suitable tool for SVG, hasn't been for many versions (if it ever was).

eddieh• 13 years ago

Because IE 8 doesn't support SVGs and still accounts for >20% of desktop traffic (by some reports). Likewise, Android 2.x doesn't support SVGs and accounts for some non-ignorable amount of mobile traffic.

Where I currently work we can't support SVGs with some projects due to a bug in the middleware we're mandated to use.

jahewson• 13 years ago

Nobody has mentioned the abandonment of SVG 1.2 as a factor. It was dropped by the W3C and never implemented in any browsers. This not only stalled improvements to SVG 1.1 but created a situation where the editing software (e.g. Inkscape) allows the user to create files using SVG 1.2 features which are invalid in SVG 1.1.

The abandonment has resulted in much-needed improvements to SVG being delayed. The last full release of SVG was 1.1 which was in 2003, we won't see another full release until SVG 2 which is expected in 2014, over a decade later!

Never mind the fact the browser implementations of SVG are still riddled with bugs and none are complete.

ahoge2• 13 years ago

we won't see another full release until SVG 2 which is expected in 2014, over a decade later!

HTML4: 1998

HTML5: 2014

pfraze• 13 years ago

Doesnt really compare

nerfhammer• 13 years ago

HTML5 has been rolling out since 2004

Tloewald3• 13 years ago

The big difference is HTML was in widespread use already in 1998. Delaying the next version update when your standard isn't very popular is not a recipe for success.

leokun• 13 years ago

More like:

HTML4: 1998

XHTML: 2000

HTML5: 2014

Also, I blame IE 6.

Recoil42• 13 years ago

Yep, this right here. I'm working on a project involving SVG right now, and support is legitimately terrible in about 50 different ways.

aj• 13 years ago

I'm looking to cook up a PoC on SVG rendering on Mobile devices. Any insights and/or information on the issues that you've faced would be super helpful

ekianjo2• 13 years ago

Isn't that also because rendering SVG on screen is way, way slower than using PNG or JPG images? There was a comparison done half a year ago between the same page full of icons rendered using PNG vs SVG and the SVG version was sluggish as hell. And that was on desktop, you can only imagine how worse would the performance be on mobile devices...

sliverstorm2• 13 years ago

Hmm... on a completely unrelated note, I may have just figured out how to convince the world that 5GHz processors and oodles of RAM are necessary in phones, thus keeping them on that upgrade treadmill...

rev087• 13 years ago

I imagine that is mostly due to the lack of attention to the format. PDFs with vector graphics work very well both in my desktop computer and mobile phone. The iPhone can even preview Adobe Illustrator files very well. Granted, it could cache the renderization since the image is not dynamic as a webpage.