I'm building a camera application that saves the image data to a single JPEG file in the sandbox. The images average at about 2mb in size.
Problem : I cannot display the images in a photo viewer because having a few images in memory throws memory warnings and makes scrolling through the images very slow.
I cannot split the image into tiles and save them to disk because that's even more expensive than displaying the single image. I tried splitting the image up into tiles upon capture, but on the 5S it took, on average, 5 1/2 seconds to save all the tiles to disk. It will only get worse from there as the app is executed on older devices. This is very bad because what if the user exists the app in the middle of the save? I will have missing tiles and no uncompressed original file to find missing tiles later.
Question : what's the best way to show a full sized image without causing memory issues and keeping the scrolling fast? Tons of camera applications on the App Store do this and the Photos app does this, there has to be a good solution.
Note : I'm currently showing a thumbnail of the image and then loading the full size image from disk in another thread. Once the full size image loading has finished, I present the full size image on the main thread. This removes the memory issues because I only have one full size image in memory at once, with two thumbnails, but still causes lagging on the scrollview because drawing the full size image in the main thread is still pretty expensive.
I would greatly appreciate any input!
you could..
create a down sized thumb nail..
create a smaller image and save that in a different "sandbox" folder.. and read that for browsing.. then after that load the image if the user wants to look at it full size.
One way to deal with this is to tile the image.
You can save the large decompressed image to "disk" as a series of tiles, and as the user pans around pull out only the tiles you need to actually display. You only ever need 1 tile in memory at a time because you draw it to the screen, then throw it out and load the next tile. (You'll probably want to cache the visible tiles in memory, but that's an implementation detail. Even having the whole image as tiles may relieve memory pressure as you don't need one large contiguous block.)
This is how applications like Photoshop deal with this situation.
Second way which I suggest you is to
check the example from Apple for processing large images called PhotoScroller. The images have already been tiled. If you need an example of tiling an image in Cocoa check out cimgf.com
Hope this will helps you.
Related
The login view in our app uses large background images. To try and save on memory/app size I resized and compressed these images, which reduced their filesize significantly (less than 1mb, down from several mb).
When monitoring my apps memory usage (XCode debugger) there is a clear spike when a modified image is displayed (around 30-40mb). I'd accepted this as normal and simply made sure to release the image asap to limit memory usage.
I've recently started replacing a couple of the images and wanted to preview the new ones before resizing/compressing them. I noticed that these images (one of which is 11mb on disk and 4640x3472 pixels) has no visible effect on app memory usage whatsoever, increasing 'Other Processes' instead (by around 20-30mb).
Can anyone explain what's happening here? I want to confirm it is advisable to continue resizing/compressing the images.
Note that I'm loading the images using UIImage(contentsOfFile:) and I resized/compressed the images using GIMP. The new images have been taken straight from Flickr and unmodified.
Cheers.
The in-memory size of the image (as a UIImage) is different to the compressed on-disk size (your JPEG)
The UIImage takes 4 bytes (RGBA) per pixel x height x with - so for a 4640 x 3472 image, you're looking at 64,440,320 bytes - quite different to the 11MB on disk
I am working on application which include native SQLite database in which I am storing and retrieving images and showing into My application.
Now my problem is Like I am storing lots of images in directory and its path storing into database. So when I retrieve that path from database and load image into application, Memory Increases upto 10-20 Mb per image.
I also tried to store image data into database but same issue, Memory increase 10-20 Mb per image.
Please what should I do for this memory issue ?
Help me with it
Images, when used in the app, may require considerably more memory than the size of the asset in persistent storage might otherwise suggest. Assets are frequently compressed (e.g. JPG or PNG), but when you use the image, they're uncompressed, often requiring 4 bytes per pixel (one byte for red, green, blue, and alpha, respectively). So, for example, a iPhone 7+ full-screen retina image can require 14mb when you use the image. So, the memory-efficient technique is to employ lazy loading, not creating the UIImage objects until you absolutely need them. And, as Jerry suggested, because the amount of memory is determined by the size of the image and not the imageview in which you use the image, if your images have dimensions greater than required by the UIImageView in which you use them (i.e. width and height of the imageview times the "scale" of the device), you may want to resize the image accordingly.
It may be the case that the images you are trying to display are much larger than they need to be on the screen. Try loading the images into memory, creating a version with the size you need, and then using that. Of course, you could implement some caching so you don't have to keep resizing the same images. But then when the original image goes out of scope, its memory will be released. If you always need your images at the same size, try resizing them before storing them in the database, but if you want to support multiple sizes (for different devices, maybe), then store the images at the largest size you need and resize for the others.
I know this is a stupid problem, but this is my first real app that I have to make, I have no one to ask and I looked up this problem and found no other similar problems.
My app crashes on real devices with no exception. I saw in the simulator that uses too much RAM and after a while I got to the conclusion that the pictures I am using are to blame.
The app is structured in this way: it has 8 viewControllers for different things: for example, it starts with one which lets the user select the avatar with which he/she will play and here I have two pictures, next is a viewController which shows the stats for that avatar and here it is another picture and so on. The problem is that each picture uses 40MB of RAM to be displayed and things add up so the app uses more than 300MB of RAM when the user gets to the gameviewCOntroller where the game is. Because of this, on devices like iPAD 2 or iphone 4 it crashes, but not on iphone 5.
I tried to set the images both from "images.xcassets" and from a ".atlas" folder, but the result is exactly the same. The pictures have a dimension of no more than 1500x1999px, they are in png format.
Also, I saw that if the app were to start directly into the gaveViewController it would use 180MB so the other viewController remain in memory or something like that. Should I "clear" them or something similar?
//-------update-------
This is what I got from Instruments:
Memory is a big deal on mobile devices, there is not a clear answer to you question, but I can give you some advices:
If your images are plain colors or have symmetric axes use resizable images. You can just use one line of pixel multiplied by with or height to cover the entire screen using a small amount of memory
Image compression doens't have effects when the image is decompressed. So if you have a png that is 600kb and you are thinking that converting in a 300kb will lower memory usage is only true for "disk space" when an image is decompressed in memory the size is widthXheightXNumber_of_channelXbit_for_channel
resize images: if are loading a 2000px square image into memory and you show it inside an image view of 800 px square, resize before adding it.You will have just a peak while resizing, but later it will use less memory
If you need to use big images, use tiling techniques such as CATiledLayer
If you don't need an image anymore get rid of it. It's ok to have an array of path to images, but not an array of full uncompressed images
Avoid -imageNamed it caches images and even if Apple says that this cache is released under memory pressure, you don't have a lot of control on it and it could be too late to avoid a crash
Those are general advices, it's up to you if they fit your requirements.
You should definitely follow Andrea's advices.
Additionally you should consider setting the image size to exactly what your need is. You're saying that you've tried to set them from xcassets so you have full control over the images you're loading, which is great (compared to downloading an image that you cannot modify).
I highly suggest you read some documentation on using Asset catalog files. This will allow you to have high-resolution image for bigger screens that also have more memory, and smaller ones for older devices, which is what you want here.
Also, note that 1500x1999px is still a very big size for most mobile devices.
More links about screen-size:
https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/MobileHIG/IconMatrix.html
http://www.paintcodeapp.com/news/iphone-6-screens-demystified
I'm developing a game with lots of graphics for iOS platform. None of the graphics are dynamic, they're all ready made images. There are 6 layers on the screen and each layer contains 3-4 graphics objects in average that constantly scroll to left, each with different speeds. So with each screen refresh about 20-25 objects are scrolled, removed from screen and added again from right. The game is universal so images of all sizes present in the resources folder.On iPads, iPhone 5, iPhone 5s it goes smooth. But on 4th Gen iPod touch I notice some hiccup.
When I test the app with Instruments, I notice a critic memory problem at start and then the problem goes away. So this is all because I load all the above graphics on application start. All the images are combined into 4 different sprite sheets. So here's my question:
Is it the weight in kilobytes that matters or is it the dimensions? I'm asking this because I reduced the size of the images by about 70-80 percents, though their height and width remain the same, but that memory problem still exists.
If you are reducing the size of the images by utilizing compression, then expect there to be delay and a memory hit as the images are uncompressed when first loaded, and they will take up as much memory as they did before compression.
The 4th generation iPod Touch probably is having some memory pressures and it will try to release memory elsewhere in order to allow for your images to load up and stay in memory. That may be the hiccup you see, as other apps, like Mobile Safari or Mail are asked to give up some memory or to terminate.
(The size the images take in the resources folder is inconsequential. It is the size they take when they are uncompressed and in memory that matters).
You could make the images smaller by making them 4bit instead of 8bit color, or you could make them monochrome. You can also use a non-retina size or smaller, and then let the OS stretch them out to fit the space required. I would try to use the best images first, and if you get a memory warning (didReceiveMemoryWarning), then reload with the images that are less dense.
you can not load all image before the game beginning, you should use the cache to control the size of the memory. And before the scenery of game change ,the release the cache ,reload the need ones.
So you must control your resource dependents in the every game scenery.
This is the common method to management the large resource application.
I have an app that has 12 images contained in an array. All these images are displayed at the same time on the screen. (1 view - 12 much wider and higher images (UIImageView's) one on another. When user does something, app moves the images, thus the view displays different scenes)
The images themselves are not too heavy (it is about 2500x5000 in size, but the whole folder with images is around 3.5 MB).
After loading, the app consumes 355 MB.
When I put breakpoint in viewDidLoad (and all images are loaded at that time), xcode shows that the app consumes only 9 MB, but in viewDidAppear it is 355 MB.
What is the reason of it? And how can I store images compactly? (As I assume that the problem is in the images).
Thank you for any help!
An image open will occupy something like : H x W x number of channel x number of bit for channel, the file size is another thing, because images are compressed according to their type. Your images are 50Mb each one in memory.
The only way is to resize the image before displaing them. There are plenty of image resizing categories online, just google a little bit.
The other suggestion is to not load all the images togheter, just bring in the array the file path, and instantiate the image lazily.
If you need to use hires images you should look for CATiledLayer and tiling techniques.
These images probably cannot be displayed all at the same time onscreen, so you may want to load them only when necessary.
If you still need to display them all together onscreen, think about reducing their size.
Still, 355Mb is huge. Are you doing anything else in that application, that might use up all of that memory?
In Xcode go to Product->Profile. You will find there a lot of useful instruments which will help you to find problems with memory, CPU or battery usage. However, check it if you haven't seen it before.