Resolution Independence?

ghost_user_name

Ok, I see this term thrown around a lot in reference to desires for Leopard, but I don't fully understand it. I tried the Wikipedia article but still don't fully grasp the concept. Does it mean that everything in the OS (icons, text, etc) will all be vector graphics rather then bitmaps? Anyone care to explain? Thanks.

chucker

Vector graphics are inherently resolution-independent, yes, but Quartz actually eventually vectorizes bitmap graphics, too. You can easily see this in the Dock, which already is completely resolution-independent and always has been. Try switching resolutions and watch the Dock not change at all (whereas all open windows will change).

ghost_user_name

That's intersting. So it vectorizes on the fly? How? I take it then the argument would be to have the entire OS resolution independant rather then just the dock.

hmurchison

jdcfsu



Here's why you'd want Rez Ind



Take the 30" Apple Cinema display. It has a resolution of 2560x 1600. Great for looking at larger items but text and other small things are pretty miniscule. Now imagine if you could "Zoom" your user interface so that text was still legible on this huge display. This would enable you to on the fly change the resolution that you see while leaving the LCD at its native resolution and thus sharpest picture quality.

ghost_user_name

Yeah, that makes sense now. Thank you. Only question that remans is how does it vectorize bitmaps on the fly? Isn't this an involved process?

mr beardsley

Quartz doesn't vectorize bitmap images, it is just really good at interpolating. The icons in the dock that Chucker mentioned are actually files that contain the image of the icon at 3 different sizes, one small, one medium, and one large. Quartz can quickly and accurately interpolate between these sizes to show an image that is somewhere in between. This makes it appear that the icon can grow and shrink like a vector. To see this in action, hold down the Option key as you resize your dock, and you will see it snap to the three different sizes. This trick also works in iPhoto.



In preparation for resolution independence, Apple is allowing icons to be created at 512x512 pixels. This ridiculously large size for an icon will ensure that no mater how large you size your interface, Quartz will have the information it needs to provide you a good looking image.

chucker

Quote:

Originally Posted by Mr Beardsley


The icons in the dock that Chucker mentioned are actually files that contain the image of the icon at 3 different sizes, one small, one medium, and one large.

Yes, and Quartz vectorizes them on-the-fly.

Quote:

In preparation for resolution independence, Apple is allowing icons to be created at 512x512 pixels.

256x256.

mr beardsley

Actually no it doesn't. Read up some more on Quartz. Quartz is nice and fast at rendering and resizing bitmap images, but not so fast at working with vectors. This is part of what Quartz 2d extreme is supposed to fix. Since Quartz works so well with bitmap images, that is why Apple still uses them for a lot of the widgets in OS X. Here is a thread on Ars that you can read.

http://episteme.arstechnica.com/grou...r/997006643731



Also here is a post that talks about making a vector a bitmap.

Quote:

No doubt, a vector image will always look sharp, as it rasters to the resolution of the output device — in this case, the screen.



On the other hand, vector oriented data is terribly inefficient for complicated images, such as detailed photos. In such cases, saving the image in high dpi raster format and letting Quartz downscale as needed may be a better solution, from a performance standpoint. Of course, at some zoom levels (that are not even multiples), the image will not look sharp and will benefit from anti-aliasing.



I'm well aware that there are a number of software applications that are designed to scale images by creating vector oriented data from the image. Genuine Fractals from LizardTech and Extensis' pxl Smartscale comes to mind. The original raster data is replaced with a new vector-oriented file structure and, thus, gains resolution independence. However, such algorithms are rather compute intensive and impractical from a real-time display perspective. Teh Snappy™ it will not be.

You are right though about 256x256. I thought I'd read somewhere that it had been upped to 512. Oops.

mr beardsley

Found it on Apple's site.



http://developer.apple.com/documenta...z2D/index.html

Quote:

Quartz draws images using an interpolation (or pixel-smoothing) algorithm that provides high-quality results when the image is scaled. When you create a Quartz image, you specify whether interpolation should be used when the image is drawn in a Quartz context. You can also use the function CGContextSetInterpolationQuality to set the level of interpolation quality in the context. This parameter is merely a hint to the context?not all contexts support all interpolation quality levels.

chucker

Quote:

Originally Posted by Mr Beardsley


Actually no it doesn't. Read up some more on Quartz.

The end result of anything in Quartz is DisplayPDF, and DisplayPDF, like all PDF, is vector-based. A bitmap image (say, a Dock icon) resides in a Quartz layer (say, the Dock) is treated much in the same way a vector image would. Scaling works so great because PDF provides for good anti-aliasing, which we also see with text. It's all smoothened out very well (although it doesn't use subpixel anti-aliasing).

mr beardsley

Quote:

Originally Posted by Chucker


The end result of anything in Quartz is DisplayPDF, and DisplayPDF, like all PDF, is vector-based. A bitmap image (say, a Dock icon) resides in a Quartz layer (say, the Dock) is treated much in the same way a vector image would. Scaling works so great because PDF provides for good anti-aliasing, which we also see with text. It's all smoothened out very well (although it doesn't use subpixel anti-aliasing).

Incorrect. PDF can contain vector and raster images. Here is an article on PDF that describes how it can contain both vector and raster images. http://en.wikipedia.org/wiki/Pdf

Quote:

A PDF file of a map, for example, is often a combination of vector graphics, text, and raster graphics. A general reference map of the US [2] uses:

text stored as such ? scalable, and also one can copy the text

vector graphics for coastlines, lakes, rivers, highways, markings of cities, and Interstate highway symbols ? on zooming in, the curves remain clear, they do not appear as consisting of enlarged pixels (i.e. rectangles of pixels)

raster graphics for showing mountain relief ? on zooming in, this consists of enlarged pixels

Some PDFs have no raster graphics at all. For example, see the Factbook's map of the Arctic.

Tools exist, such as pdfimages (bundled with Xpdf) to extract the raster images from a PDF file. This can be useful if the PDF is a collection of scanned pages. Xpdf can also make raster images from complete pages that included vectors.

chucker

Quote:

Originally Posted by Mr Beardsley


PDF can contain vector and raster images.

I know that. I think I'm just not making myself clear. Never mind.

icfireball

Interesting that when you use Universal Access' Zoom feature - text is not resolution independant.

jll

Quote:

Originally Posted by Chucker


256x256.

512 x 512!

chucker

Quote:

Originally Posted by JLL


512 x 512!

http://developer.apple.com/releaseno...pendentUI.html

Quote:

Icon Services in Tiger has been extended to support icons that are 256 x 256 pixel in size.

jll

We're talking about Leopard I assume.

chucker

Quote:

Originally Posted by JLL


We're talking about Leopard I assume.

Apple hasn't published any Leopard-specific ResInd info.

ghost_user_name

Well thank you all, you have helped to clear up not only what it is, but a bit on how it works. Thanks again.

jll

Quote:

Originally Posted by Chucker


Apple hasn't published any Leopard-specific ResInd info.

So? I was kindly telling you that Leopard now allows 512x512 icons.