I am developing an app for a magazine and simultaneously I am creating images for those magazines using photo shop.
But, when I zoom these images, the text quality is getting loosed.
I have referred to other iPad magazines like India Today. In that, even though I zoom to maximum extent, text quality is too good.
how is that possible? My each image size is almost 800 KB. Even then, when I zoom, I loose the clarity of image. How to maintain the quality of text even when I zoom?
Is that something to do with photoshop editing or coding?
We use the following table for our iPhone/iPad projects when the OS target is 3.2 or above.
Because you are using raster graphics you are in a losing battle of file size vs. zoom quality. Text is natively vector and scales beautifully as you zoom, so you are much better off rendering text as text rather than generating text as an image in Photoshop. There are many ways to accomplish this, one being to have the image be a background layer and the text be a UILabel above the image.
Related
I have an image with the dimensions of 5534 × 3803, and size of 2.4mb. The UIView references notes that:
"In iOS 3.0 and later, views are no longer restricted to this maximum
size but are still limited by the amount of memory they consume."
When the image loads, it lags for half a second, then slides in. The image sits in the UIImageView at 1024x704, but can be scaled up to 4x that size for the purpose of my app.
Are you able to preload the image in the AppDelegate? Or is there another way of working around having such a large image?
Thanks
EDIT: The scaling is done via UIPinchGestureRecognizer, and scales up and done (scale x4 - x1) based on the image's center point. There is no panning of the image when zoomed in.
Personally, I would try to write a tile-based system (think Google Maps) that slices your big image into a grid of small images to avoid loading in that gigantic image all at once into RAM. I don't really know what your user interactions are for this image, or whether the images are changing or baked into your project, but I'd assume you can let users scroll around since that image is bigger than any iOS screen. With a tile-based system, you only load the images that are on-screen. CATiledLayer is an Apple class for doing just such a thing. That's probably what you want to look into.
See this StackOverflow question for some different approaches. The accepted answer uses code from Apple's sample PhotoScroller project, which may work for your needs and uses CATiledLayer.
This ScrollViewSuite Apple code might also get on your way (check out the Tiling code).
I have been trying to render PDF documents into a CATiledLayer, but this appears to be slowing down the rendering process on the iPad.
I've also tried using a normal layer, but I've not seen an improvement.
Is there any alternative to using a CATiledLayer for rendering a PDF?
CATiledLayer is necessary either by itself or as a backing layer for a UIView when you are attempting to display a view or layer that exceeds the maximum texture size supported by the GPU. Apple lists this as 1024x1024 for the iPhone, but in my experience I've been able to go up to 2048x2048 on even the first-generation iPhone.
If you are able to render to a view or layer that is smaller in both width and height than those dimensions, you don't need to use a CATiledLayer and can get away with a standard layer. The tiling process does slow rendering a bit as it brings in the appropriate tiles, so you could gain some performance that way.
For a discussion on general PDF rendering performance, I direct you to this question:
Fast and Lean PDF Viewer for iPhone / iPad / iOs - tips and hints?
I have an application that let's users view images. The user decides what images to use, so the size can range from 10x10 to 10000000x10000000 (I am exeggerating). All is well up to a certain size, when the image is bigger than the iPhone's memory. Quite understandably.
But how do I fix it? Is there a way to load only a portion of the image (I'm using an CATiledLayer, so I could load/release tile by tile).
Thanks in advance!
Unless you have an uncompressed image format it would be very hard to load the image in patches, you will have to provide the patches that the user would load, determine what portion of the image to show, and load the correct patches. There is an example for this "ScrollViewSuite" that demonstrate that technique. But this technique does require a preprocessing step.
I’ve been busy working on the graphics for my iPhone application. I started working on generating icons for my UITabBar and ran into lots of problems. How do you create these icons?
I created this solution:
http://www.nailrails.com/?p=46
Are there any shortcomings to this approach? It seemed to work for the few icons I created...
Apple's guidelines can be found at http://developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/MobileHIG/IconsImages/IconsImages.html#//apple_ref/doc/uid/TP40006556-CH14-SW1
The docs are pretty straightforward-- alpha is all that matters when the image gets loaded by the toolbar, meaning that anything that's not at least semitransparent will render in the same opaque shade. As for how I do that, I mainly use Adobe tools. Fireworks is my preferred tool but Photoshop's also more than up to it. Another one I've had good results with is Acorn, which is frankly a lot cheaper while being more than sophisticated enough for this kind of work. I'm not really a graphic designer but a certain familiarity with this kind of stuff goes with the job.
I have an article up on my site that shows how to use OmniGraffle with a template I use to create great iPhone toolbar icons in minutes:
http://steveweller.com/articles/toolbar-icons/
The template sets up a grid to work to that corresponds to one square for each pixel. You draw your icon in white on top of the black template background and then export as a PDF exactly the right area to match the icon size you need (typically 21 pixels high). Then you reimport the PDF, resize it to the final icon size (21 pixels again), and export as PNG. The template does nothing magical; it just provides an already set up working area and helps you get the final PNG right every time to the scale is correct.
You could use the same technique in Acorn or any other app that supports PDF export and layers.
(I use Gimp. Assume your icon layer already has alpha channel.)
Right click the layer, then add layer mask.
Done with option "transfer alpha channel of layer" chosen.
Select the whole layer (but not layer mask), and clear it with pure white.
Resize image to Apple-suggested size, and export it as png file.
You may also paint directly on the layer mask.
I'm writing a small program to convert a standard definition 4:3 video to a hi-def video 16:9 and I'm experiencing a serious stretching effect, as expected I suppose (though I didn't think about it until my code started working). Anyhow, the only way I can think of getting around this stretching effect and still fill the whole 16:9 screen is to cut off the top and bottom of the image.
1) So my question is, when converting from SD to HD, do I have to lose image parts of the image in order to fill the whole screen without any stretching effects?
2) Same question for converting from HD to SD.
I'm new image processing, are there any popular approaches to reducing the stretching in these kinds of operations? Is there a smarter approach to this problem than just cutting off parts of the image or introducing black bars to the image?
Thanks in advance for all your help!
Other than the obvious methods of cropping, letterboxing, and pillarboxing, which either lose image data or necessitate potentially-undesirable black bars, there is also adaptive image resizing. Basically, the intent of these techniques is to be able to create a version of an image with an arbitrary aspect ratio, without losing the essential characteristics of the image or distorting it. One technique is called seam carving, and can be seen here.
If you'd like to test the technique out on some images of your own, the functionality is included in recent versions of ImageMagick, as explained here.
Reduction of quality or loss of content is always a problem in resizing images or video. Generally you scale the image in one direction, and either trim or pad the other direction.
On TV it is common to cut off the left and ride side of a 16:9 frame to put is on 4:3 screen, and to add black side bars to go from 4:3 to 16:9. TV editors don't cut off the top and bottom of a 4:3 frame to fit it on 16:9 because there's almost always important parts of the scene there. The far left and far right of a 16:9 frame don't usually have important elements, although in some cinematic scenes losing the sides makes a huge difference.