Res. #534 - T-Mobile Permit.Doc: Fill & Download for Free

WebKit deals in logical pixels and a device pixel ratio to render stuff. It knows nothing about the physical pixels of the display. So when you really have 640x960 pixels on the display, your iPhone's Safari will tell you that you have 320x480 pixels to work with a device pixel ratio of 2. If you try to supply an image without any hints, it'll try to render the image at 1x scale in twice the width/height you want (which will be upscaled). However you can give it some hints to tell it what to render at. And this technique is applicable both to iOS devices (which have 1x and 2x scale devices) and Android devices (which have 0.75x, 1x, 1.5x, and 2x scale devices).Let's pretend you have a source image that is 200x200 at 1x scale, and 400x400 at 2x scale.If you'd like to use <img> tags to render images, you can pass your 2x scale image as the src, as long as you set the width/height to 200x200 (either as tag attributes or as CSS styles). This is generally not preferable, as you can't really differentiate between different scaled devices this way (unless you're using JavaScript, and at that point you might as well use the next technique). But if you only want to make one asset one time, and don't mind the extra bandwidth, you can use this approach.The best approach is to use CSS background and background-image to supply your images. The trick here is to use the CSS background-size property to set the render size of the image at 1x (in this case, background-size: 200px 200px). You can combine this with CSS background-position to achieve sprited assets (where you put all your images into one giant image and slice out the relevant parts of it).The big advantage here is that you can target specific screen scale factors with CSS, using a trick known as CSS media queries. This lets you specify entire CSS files, or parts of CSS files, to load for devices at 1x scale, at 2x scale, and other scales (as well as ranges of scales). This means that 1x scale devices are only loading 1x assets, and 2x scale devices are only loading 2x scale assets. The best way to do this is split your assets into multiple CSS files, and load them using the media attribute, like so:<link rel="stylesheet" href="1x.css" media="only screen and (-webkit-device-pixel-ratio: 1)" /><link rel="stylesheet" href="2x.css" media="only screen and (-webkit-device-pixel-ratio: 2)" />You can also do this in one CSS file like so:@media only screen and (-webkit-device-pixel-ratio: 1){.image{ ... }}@media only screen and (-webkit-device-pixel-ratio: 2){.image{ ... }}There are also -webkit-min-device-pixel-ratio and -webkit-max-device-pixel-ratio selectors you can use, so you can use specific assets for a range of device pixel ratios (which matters if you're targeting Android). The scaling will Just Work across all device pixel ratios when you do this.You can also query for this property in JavaScript. window.devicePixelRatio will return 1 for 1x scale, 1.5 for 1.5x, 2 for 2x, etc.UPDATE: As of iOS 5.1, it appears there is an issue with high-resolution JPG images being presented in this manner. WebKit on Retina iPads will downscale the image and then upscale it again, leading to a significantly uglier image. The only known workaround is to use PNG images instead of JPGs (which obviously sucks for high-resolution images, which consume significantly more bandwidth than JPGs). Apple has been made aware of this issue: rdar://problem/11097671. If your image contains greater than 2 * 1024 * 1024 (2097152) pixels when you multiply the width and height together, you must use PNGs, or the image will not appear crisp on the Retina display.UPDATE 2: There is supposedly a way to work around this, by saving JPEGs in Progressive mode. There is a "Progressive" checkbox in Photoshop's Save For Web which enables this. I haven't tested this myself, but multiple people have reported that it works. Thanks to Iain Anderson in the comments below, as well as codezero on Hacker News.

The short answer would be Yes.The slightly longer answer would be Yes, but what are the actual costs for high-res audio? There are additional “costs” on compressed audio too, so what costs do we consider the highest? One need to realise that the main difference between compressed music files is the file size and that there is a quality loss when reducing the file size.Explicit costs refered to high-res audio:Storage requirements - Large music files require a larger space to be stored. Storage are however rather cheap today, so this is not much of a problem anymore, other than when storing a personal music collection on a mobile device. On the other hand, the reason for storing a complete music collection locally is now made redundant by high quality streaming services (such as Tidal, who offer streaming of music files, not in high-res quality, but in CD quality e.g. better than the lossy compression formats such as mp3, ogg and Apples similar versions).Bandwidth requirements - Large music files require more bandwith to be distributed, within the wi-fi network at home or when distributing the music through the cell phone network.Explicit costs referred to lossy compression formats (and to some degree also applicable to the CD standard format):Conversion requirements - Lossy compressed music data need to be both packed (compressed) at some point in the production process or done by each one who start with a lossless music file and want to make a lossy “copy” of it. Every time the lossy compressed file is to be played the file needs to be un-packed to be converted to sound. Both of these processes require time and processing power. One might say that playing lossy compressed files on a mobile device is a trade off between battery requirements (additional power that is needed to un-pack the music file on the limited memory) and storage capacity. There are however other reasons why this might not be that a big deal depending on how much power a larger storage might require and how efficient the un-packing process is.Fidelity quality - There is always some fidelity loss introduced when converting a music file to a file with less capacity (FLAC and zip files maintain the data intact and thus do not suffer from any fidelity losses). The fidelity loss is not allways that obvious, but there are always one and how much it affects the listening expreience is not easy to measure. I would say that the risk that a piece of music that listened to in a high-res format, a piece of music that could make one feel better in some way, if a lossy compression would ruin this opportuinity, I would say that is a high cost. Not sying it is always the case, but it is a risk I think rectifies aiming for high-res audio instead of lossy compression formats.