I'm working with UIImage and like everyone else have to deal with retina and non-retina display adaptability. As for as I know, retina display requires double pixels.
I'm wondering if I could simply use a large image with the same width/height ratio, just resize it smaller to adapt all device?
For example, I made a original image with size of 200*200 pixel. Now I want to use it in application as 20*20 pixel, and 80*80 pixel (two situations). Then I have to make four copies like img2020.png, img2020#2x.png, img8080.png and img8080#2x.png
So if I want to use it in three situations with difference size, I have to store 6 copies. Can I just use UIImage's resize function to do this? I've tried a bit but cannot figure out it's quality and performance.
Any ideas? Thanks a lot :)
All native API suppose you to use image.png and image#2x.png, so it may be difficult sometimes to use just one image and scale it depending on retina/non-retina. Moreover using retina graphics on non-retina devices lead to more extensive use of these devices' resource causing battery drain. And, of course, if you have many images, that will decrease performance of your application. In other words there are reasons to use double set of images and you should better use it instead of one large image being scaled.
You don't need to make 6 copies. You should use the size 200*200 pixel. And set the property contentMode of imageview to aspectFit. Or you can also use below function and change the size of images at run time.
-(UIImage *)Resize_Image:(UIImage *)image requiredHeight:(float)requiredheight andWidth:(float)requiredwidth
{
float actualHeight = image.size.height;
float actualWidth = image.size.width;
if (actualWidth*requiredheight <actualHeight*requiredwidth)
{
actualWidth=requiredheight*(actualWidth/actualHeight);
actualHeight=requiredheight;
}
else
{
actualHeight=requiredwidth*(actualWidth/actualHeight); actualWidth=requiredwidth;
}
CGRect rect = CGRectMake(0.0, 0.0, actualWidth, actualHeight);
UIGraphicsBeginImageContext(rect.size);
[image drawInRect:rect];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
I made some comparisons before. Leaving iOS handle the resizing causes lower quality, and really unacceptable sometimes.
I feel lazy sometimes, my approach is to run it with the retina version, and if it looks bad, I will create a low-res version.
If you're writing an iPhone-only app, most of iPhones on the market has retina, so I don't think you should worry about non-retina version. Just my opinion though.
Related
I'm trying to show image in my iOS APP.The image is of 10000x8000, which is much higher than iPhone's screen resolution, if I add it to UIImageView ,the APP will receive memory warnings and lead to crash.Can any one give me a advice about how to deal with it? Thanks a lot.
This is the sample app from apple which displays large size image, it uses TileImageView scale the image and reuse tiles according to present zoom.
https://developer.apple.com/library/ios/samplecode/LargeImageDownsizing/Introduction/Intro.html
Or if you simple want scale down the image, you could use this.
+ (UIImage*)imageWithImage:(UIImage*)image
scaledToSize:(CGSize)newSize;
{
UIGraphicsBeginImageContext( newSize );
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
This is just a side note and not an answer.
#AmitTandel's answer will surely help you but,
remember, you should not always request for this high resolution image instead you should implement a logic which stores this high resolution image to somewhere after reducing it using #Amit's answer. And then at the time of re-requesting for the same image url, you should first look up in to your stored directory, if that image not exist only then you may request for an image.
But yes, I'm not suggesting you to follow my answer as you will require to download this very high resolution sized image (which is actually none of use), so if you're getting this image from your server, you can ask them to give you reduced size for images. I've heard that, they can reduce images to different sizes to help apps showing specific images at variant places.
Is it possible to target users that only have retina displays/have a particular version of iOS? If not, do I need to include non-retina images in my project? I know that for the application icon it needs a non-retina version, but for all of my custom graphics, such as UIBarButton icons, etc. do they all need to have both a retain (test#2x.png) and a regular (test.png) version?
Also, how should I go about scaling? Currently I'm creating say a larger image, like 100x100px and then scaling it down with the following code:
// grab the original image
UIImage *originalImage = [UIImage imageNamed:#"test.png"];
// scaling set to 2.0 makes the image 1/2 the size.
UIImage *scaledImage =
[UIImage imageWithCGImage:[originalImage CGImage]
scale:(originalImage.scale * 2.0)
orientation:(originalImage.imageOrientation)];
Does this maintain a higher resolution than if I re-sized it to 50x50 pixels in photoshop and then added the file into my project as is?
You cannot specify users device.
You'd better add two versions for all images into your app.
Because you could not know whether the device is retina or not.
I hope this is a quick fix.
I'm trying to repeat a UIImage as a background texture and of course I want to accomodate for Retina display.
I have a background image (22px wide and 640px tall) that I want to repeat on the x-axis (it is oriented to Landscape) but have it scaled down to 11pt wide and 320pt tall. I tried:
UIColor *c = [UIColor patternWithImage:[UIImage imageNamed:#"bg#2x.png"]];
[scrollView setBackgroundColor:c];
and it does not scale down, though it does repeat.
Any suggestions to how I can scale it down?
I guess I'll write this as an answer, but the main problem (for the scaling at least) is that the system does not know that it IS in fact a retina image. It needs to search for the filename without the #2x, and then if there is an #2x, it will know it is supposed to be a retina version and thus will be scaled down.
ie. just do
[UIColor patternWithImage:[UIImage imageNamed:#"bg"]];
Suppose I want an image to be 320x100 points for a retina screen, I would have to make an image 640x200 pixel and named it #2x. The problem is when I download an image from a web service of size 640x200 pixel. Normally a #2x image would be translate to size 320x100 points in the phone, but the image from the web service is still 640x200 points.
Note - the web service is my own, so I can fix it if it's the web service's problem.
Sorry If might have not worded the problem well, but this is what I meant(similar):
Retina display and [UIImage initWithData]
You'll have to set the height and width of the control in points manually and it will automatically display the image with a higher DPI without unnecesarily downscaling.
An #2x image will always be twice the dimensions of a non-retina image if it wasn't loaded through imageNamed.
Create an image like so on a retina and non-retina device:
UIImage *anImage = [UIImage imageNamed: #"anImageName"];
NSLog(#"%#: scale: %f", NSStringFromCGSize(anImage.size), anImage.scale);
The CGSize object printed on the retina device will be the same size of the non-retina image, but will have the scale set to 2.0.
Creating an image using the explicit retina suffix will reveal that the image is actually twice as big - so imageNamed does its own image scaling.
For the case where you want to display this in an already created and sized image view, you still don't need to do anything - just load it straight in and the image view will adjust the image to the correct size.
If, however, you want to create a new image view, then you'll need to create a frame paying attention to the UIScreen's resolution like so (unfortunately, you can't just set the scale property as its read only):
CGRect newFrame = CGRectZero;
newFrame.size.width = (anImage.size.width / [UIScreen mainScreen].scale);
newFrame.size.height = (anImage.size.height / [UIScreen mainScreen].scale);
This assumes that your web service is aware of wether the screen of the device is retina or not; some services will pick this up automatically, some will require you to tell them this up front. YMMV.
I have developed an small iOS app, where i have image named bg.png which is of dimension
1024 * 768 for iPad.
Now i have many images which has been created for iPad size. Now i need to make support of this app in iPhone, for that weather i need to create same set of images agian for iPhone size,
568 * 300 for iPhone.
or there is another way to do this?
Scaling down the iPad image assets will destroy UX on iPhone. Also images like icon, splash screen usually contain company logo. Scaling down will tamper the look of the logo and overall image. Better way is to create separate images for iPhone form factor. Trim the png files using http://tinypng.org/ to keep binary size low.
Cheers!Amar.
You can use this code to re-size the image by following code,
CGSize newSize = CGSizeMake(568, 300);
UIGraphicsBeginImageContext(newSize);
[yourIpadImage drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
newIphoneImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
//UIGraphicsBeginImageContext(newSize);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
You have option to change the Size of Your Image
sathiamoorthys solution is a difficult way or rescaling your image. You can do that by simply creating a UIImageView, initialize it with a UIImage and then change its frame.
Note that your image will look scaled/distorted that way.
follow this:
open the image in preview.
go to tools > adjust size
put in whatever size you want.
save the image as a different name.
yes
you should create duplicate and resize them for iphone. Using same images for iphone will bring memory issues because the images are unnecessarily big for iphone.
Use any software to resize them or you can do this using preview also as Nikita described above
If you are doing this to create universal app then you must postfix ~ipad in the name of the image file.
Please visit this link, May help you and solve your issue.
There is the some tips like:
Propotional scale,
Resize
If you want your images to show up unscaled, you are going to need an additional image with the correct size.
So supporting both iPad with and without retina screens would require one image of 768x1024 and one of 1536 x 2048. For iPhone 3.5" you would need 960 x 640 when it is a retina screen or 480 x 320 when it is non-retina. For iPhone 5 (4" screen) you would need 568 x 320.
If you use UIImages method imageNamed: there is help from Apple. It loads on retina devices that method looks for the the image you specified with the postfix '#2x'. So you can simply code:
UIImage * myImage = [UIImage imageNamed: #"myImage"]
If you make sure you project contains myImage.png for non-retina devices and myImage#2x.png for retina devices the right image gets loaded at runtime.