Our graphics guy just gave me the sliced images for an Application we're building, but he only gave me the resolution for the 960x640 iPhone 4 res.
And advised that I can just scale the images down for 3g at runtime, so the resolution/image size remains the same but it's just displayed at half size.
The question: Is this allowed when submitting to the app store, or is it a requirement to have for example:
IMAGE1#2x.PNG (460x640) - iPhone 4
IMAGE1.PNG (230x320) - iPhone 3g
For all images.
I might just do the batch conversion and have two resolutions for all images, to save maximum space.
That's allowed, but obviously the images will occupy four times as much RAM on the older devices than they otherwise would, having four times the pixels. While the iPhone 4 has 512mb of RAM, the 3G and the original have just 128mb. Though assuming you are dealing with memory warnings correctly and everything will still fit, the main side effect will be performance issues whenever things are purged and later reloaded from disk (which, as I'm sure you're aware, is handled automatically for view controllers in NIBs). Based on empirical observations, the flash memory on pre-3GS devices is a lot slower than the later stuff so even if you're sticking with the large images it would make sense to attempt to minimise on-disk size.
Best practice that has worked for me is to make my retina image, then scale it down by 50%.
In order for the retina display to use the larger image, the #2x MUST be apart of the larger image. Your example is the way it should be used.
I would do the batch scaling ahead of time for sure. If for no other reason than the iPhone chooses whether or not to display the IMAGE1.PNG or the IMAGE1#2X.PNG depending on the resolution of the screen. In your code you always just reference IMAGE1.PNG. You don't have to make any coding changes. If you scale them at runtime you will have to override all of your calls to any UIImage type of thing.
IMHO, You are likely to miss one or else Apple is likely to release a different configuration of phone that will cause you to have to rework all of your code that is checking for screen resolution.
Related
I have 2 iOS apps that have been in the market, 3 years on iPhone, 2 years on iPad HD version. The apps are a popular reference tool in the medical field. They are both comprised of 1100+ images. The current app size is roughly 52mb.
Approximately 400 images will be redone. They are currently jpg and low resolution. The replacements will be png, with higher resolution.
I'm uncertain on pixel size for these images. If they are in the 280x280 range, each file is about 100k, if in the 560x560 range, each file is almost 400k.
So I'd be looking at additional 40mb for the smaller images and 160mb for the larger.
There are plans for another 400+ images in the near future. So, I'm somewhat concerned with final app size.
If I went with the larger size for Retina devices, can I downsize for non-Retina devices?
If I supplied both sizes, image.png and image#2x.png, that would be 200mb just for these images.
I'm a little uncertain on how to manage these with regards to their individual size and, more importantly, their total size.
Any comments or suggestions are welcomed and would be helpful.
TIA,
jb
Here are a few options you have:
1. Downsizing Retina Images
I would not recommended downsizing retina images for the non-retina devices. This produces non-optimal performance and makes the images look bad. Your still loading in all the pixels of a retina image, but only displaying 1/4 of them.
2. Bundling All of the Images
Honestly for a medical reference app, I think it would be understandable if your app size would be quite large. I wouldn't imagine people would need to download this app over 3G or LTE. Your users understand this is a large database app which provides high resolution images, thus they should be okay with the large app size via this method.
3. Hosting the Images on a Web Service
Another alternative would be to host the images on a server, allowing them to be downloaded individually as needed, or in bundles. I think your users would prefer being able to fully use the app without internet connection rather than having a smaller app size.
4. Alternative Image Loading
This approach takes a bit of work and could be a little risky. You could bundle only 2x versions of your images into the app. Then on App launch you could force the user to wait until you resize all the images to their 1x counterparts and save them off to the disk. Then you could create an image loading convenience method which loads a UIImage from either disk or the app bundle based on whether or not it needs a retina image.
I definitely recommend option 2 for your purposes. I only mentioned the others to be thorough.
Is there a way to not add 1x images to an iPhone/iPad app?
I'm developing an iPhone app and also testing on my iPad.
When I just use #2x images, the iPad successfully resizes down to the 1x size.
Is there any downside to not to add 1x images? Or are they still important?
By forcing the device to downsample, you're sacrificing performance and memory for a negligible amount of disk space. It's a really bad trade-off. Plus, downsampling a larger image on the fly on the device is likely to use a lower-quality downsampling algorithm than what's available in, say, Photoshop (for performance reasons).
I had an app with 100+ near-fullscreen photos, and dropping the #1x versions made possible to keep the app below the 50 MB limit for downloading over a cellular connection.
In my case, I had no choice, but as #Kevin Ballard mentions, perhaps the trade-off is not worth it. Remember that non-retina images are 25% the size of the retina ones, so in terms of pixels you are only going from 1.25 to 1.00.
Granted, with compressed images the relation might not be linear (i.e., #1x PNG/JPEG may weight more than 1/4 of the equivalent #2x image on disk).
I have a question RE Retina display graphics (and potentially iPad 2 graphics if the rumours of double resolution displays are to be believed).
Is there any advantage to having two graphics:
Graphic.png 480x320
and
Graphic#2.png 960x640
and letting the iPhone use the #2 version for retina displays rather than just having Graphic.png at the higher res and letting iPhones with normal displays squash it?
Yes. If you didn't use two separate graphics (normal and "#2x"), any device without the retina display would have to store its graphics using four times as much memory. It's a simple matter of storing an insignificant amount of compressed images (PNGs) so you don't have to kill legacy devices' memory.
Not only that, but performance will drop from having to handle such large images on devices that are generally slower.
Finally, the result of scaling huge images is usually really ugly, because UIKit uses the nearest-neighbor algorithm when scaling.
i just have a 3gs for testing (here in romania i still cant get a iphone 4)
When I just create full screen images for iPhone 4 .. would they be displayed resized on the 3gs?
I just cant make a bundle version for 3gs and 4 with 2 times my images, they are already a lot. Do I have to make now 2 Apps ??
Could this be a trick: In my xib i define a 320x480 UIImageView (it will be resized automaticly on the iPhone4) when I there define "scale to fill" and make high resolution images, would they come more sharp on the iPhone 4?
Now I am just wondering how to work best right now for big animations.
thx
Just found out in my case its fine to use higher resolution pics into a 320x480 frame like for 3GS and make Aspect FILL.
When I test on a iPhone 4 Simulator it shows much higher resolution and same on iPad if I click 2x :)
you can also create alternative high resolution images with a name ending in "#2x". so if you have an image called "arrow.png", create one with twice the resolution called "arrow#2x.png" and the iphone 4 will use that.
check out this article: http://thomasmaier.me/2010/06/dealing-with-iphone-4-resolution-2x-inside-of-photoshop/
Try it and find out, but my suspicion is that even if they do work, they won't work on OS 3.0 or OS 3.1, and plenty of people have not upgraded yet.
Also note that even if it displays them at half-size, I'm pretty sure that they'll still be "#2x" images. This means they'll use more memory and generally perform worse.
What's wrong with adding a handful of new images? The normal-size images are a lot smaller than the #2x images.
EDIT: If you have a lot of images, you may find it beneficial to use JPEGs where appropriate (e.g. for photos or photo-like backgrounds). I'm not sure, but I think they should work with +[UIImage imageNamed:] though you might have to specify ".jpg" explicitly.
So I'm building an app for 4.x devices and I'm wondering if I can just use one set of assets at double resolution instead of one set with a #2x id and another set without.
Basically im asking can the older 3g and 3gs just use the #2x assets? and do the right thing with them?
anyone have experience with this?
Thanks
You're better off using two sets of resources, one for the high resolution retina displays and one for the older displays. Downsizing #2x graphics won't look pretty and will impact performance, especially on 2G iPod Touches.
The older devices can use the #2x but as far as I understand you'll need to:
Set your UIImageViews to scale the images to fit.
Hardcode image references to the new images.
Expect poor image quality and slower performance on non-retina devices.
Overall, it's better to provide two copies of the images, "bob.png" and "bob#2x.png" then reference them in code as "bob.png".
NB. As of iOS4 you can reference the images without their file endings, so just "bob" would work; however this has compatibility implications with devices running pre-iOS4 : the images won't be found. So for maximum compatibility include the file endings if you intend on deploying to both iOS4 and iOS3.x.
They technically can, given you make sure they're scaling the right way (e.g. if it's an image view that it's set to scale up/down).
However it's not recommended in most situations, mainly because it'll be slower, uses more resources, and leads to shorter battery life. Also, depends on your resources but an artwork scaled down by a factor of 2 doesn't have the same quality as one that is resampled specifically for the new size.