I am trying to build an application to vary the contrast,brightness etc of the Image and display it.I am not able to handle large images.Is there any way I can handle Large images without losing Image quality?
PS:I have done quite a lot of search on the topic and was not able to find any solution.
Thank you in advance for your valuable suggestions.
It's going to be hard to answer your question without examples. However, I would advise you to review this article that specifically deals with how to handle Loading Large Bitmaps Efficiently.
The article covers how to:
Read Bitmap Dimensions and Type
Load a Scaled Down Version into Memory
And yes, I know that you are not wanting to loose image quality, but this article gives you the best guidelines to follow and should get you close to what you want. There are cases where you will need to scale the image down and cases where you do not need to do so.
Related
I'm a newcomer in development of android apps. But, I'm undertaking what feels like a large project and I'm looking for information on whether it will work or not, before I get to far in.
As I've read, when trying to display very large images in android, it is most useful to use the "webview".
So, I took that advice, split my image into 1024 smaller images, and laid them out in an html table (not quite finished yet). Now, I'm noticing as the table gets larger my phone begins to lag upon scrolling.
My question is, is webview trying to render every single picture at once upon loading? If so, is there a way to make webview only render a set of images at one time? Let's say I'm at 14,000X x 24,000Y on the image, can I set webview to render the next 5,000px in each direction only, or is this necessary at all?
I can't seem to find the information I'm looking for, but will continue to search. Otherwise, any and all help is appreciated. Thanks!
i have exactly same problem and i found use full this library:
https://github.com/nostra13/Android-Universal-Image-Loader
you can configure a lot of parameters and using cache..
I have 3 sets of 50 images and I have to create the animations for each set of images in Android application. I am able to create a simple application which animate first set of 50 images using the below method,
Added Animation-list xml in drawable folder and called it using frameAnimation.start().
This method didn't work until I kept the following "android:largeHeap="true" in manifest file.
I am not sure whether this is the good way to animate the images (if we have more number of images and each image of more size like 60 KB. Image is JPG format) or not
I browsed and I found that, if we are able to clear the memory and if we are able to maintain less number of images in memory, then our application will work very fine. So I want to know how to clear the memory?
Please let me know do I need to follow different method to animate the images other than I explained above, so that I can clear the memory.
Thanks for your help.
After looking into several posts and doing much research, I finally ended up modifying the images in Imageview programmatically to simulate frame animation. That way I am just maintaining three images in cache at any point of time (previous, current and next one). I hope that this will be useful to others.
It is not a good thing to process a large amount of images in a frame like manner in Android itself as it will trigger the dreaded "Out of Memory" exception.
Clearing the memory itself is not possible. The best fix for this is proper bitmap handling of the app.
I'm not sure but you might want to check on PhoneGap.
Its an HTML5 Engine that we used before to create a game.
By drawing into the canvas itself, we've recreated frame animation with it. It just requires WebDev skills though.
Ive been using various lazy loading techniques for images and other things. It works but I was wondering if there is a better way that some one knows of for getting an image from a server/webservice/whatever that doesnt require as much memory or time to download. The reason I ask is because I have an overseas developer asking me to rebuild a webservice for a project and hes asking me to allow them to just use a url to get the image. My thought was that whether its a url or a post to a service the result still has to come back via an inputstream which is going to take up the same memory whether virtual or stored in hard storage. His question had me slightly confused so out of curiosity Im asking on here......is there a way to get an image without using an inputstream? I guess it would be like a calorie free image lol.
You can blit the big image into a small image and discard the big one. This is how thumbnails work in image programs.
I have to believe there's a way to clear image data from memory once it's no longer required, but despite exhaustive searching I can't find a solution. Both stack and the google android dev list are full of questions regarding OOM errors, specifically "bitmap size exceeds VM budget", but I still don't see a clear answer.
I understand there are hard memory limits on devices, and I understand it's not realistic to load up and display or cache large amounts of image data, but there should be away to discard data that's no longer required.
For example, imagine this very basic hypothetical app, that emulates a lot of the behavior of the native gallery app:
An image gallery that allows the user to peruse images from a remote server.
There might be any number of images on that server.
The app displays 1 image at a time, and allows a user to go back or forward 1 image at a time through button presses or swiping.
There'd be a maximum of 3 images rendered at any one time (so the user can see the one immediately to the left or right of the current image when swiping). All other image data should be discarded.
Images are loaded using URL.openStream and Drawable.createFromStream or BitmapFactory.decodeStream. Streams are closed appropriately.
Images are sized appropriately on the server before being fetched.
Loading happens in AsyncTasks. Tasks that are no longer needed (due to moving away from an image with an incomplete task) are cancelled. Any references in the AyncTask are WeaklyReferenced.
When any image is no longer required, it's "cleared" via:
getBackground().setCallback(null)
Listeners are set to null
setImageDrawable/Bitmap(null)
removeView
This simple construct, that takes into account all the suggest practices I'm aware of, will inevitably crash with an OOM error at some point. Using BitmapFactory.Options inSampleSize and inPreferredConfig will delay the inevitable, but not forever, and at the cost of image quality. In this example, I've used remote images, but the issue exists with images stored in /assets/ or in internal memory, etc.
My feeling is that if we can display X amount of image data at one point, and we take all steps to remove that image data from memory, we should be able to display that same amount of data later, without having to compensate for what has happened before.
With the sheer quantity of questions about this very issue, I'd hope to have a standard solution documented, but if there is one, I can't find it. I've seen answers posted by Romain Guy, who otherwise seems very generous with his knowledge and active in the community, that say something like "Simple. Don't use so much memory". OK. Tell me how.
I should also mention that System.gc does nothing to help this. I'm also aware of bitmap.recycle, but unless I'm mistaken this can't be used in this fashion.
Am I missing something fundamental? Is there a way to discard image data once it's no longer being used? What is missing from the above to create a simple photo gallery? Assuming the built-in gallery app uses the framework and not the NDK, I imagine there has to be a way...
TYIA.
/this question has also been posted on the android developer google group list.
Through my work with Prime I found a few tips, one of which you have not mentioned. When you decode your Bitmaps make sure to use the inPurgeable and inInputShareable flags in your BitmapFactory.Options. That will help a little bit but I would recommend you look at my implementation of image loading in Prime. I use it in all of my products without any memory issues. I have found that 95% of memory problems are from the incorrect usage of the Bitmap class.
There is a very detailed article about the use of bitmaps on the android developer website.
Did you look at it ?
It explains how to load, cache and display bitmaps efficently and how to get rid of this famous OutofMemoryError.
There is also a sample application from an image gallery.
I think that's what you're looking for.
I've got an app where the main viewing area is a WebView.
It's a service where a user can also upload a photo. However, with the WebView, and photo uploads, I'm getting some OutOfMemoryErrors.
Usually all it takes is a page loaded in the WebView, and then simply trying to open an image with something like this:
Bitmap bmp = BitmapFactory.decodeFile(path);
The only reason I need to open the file at all is so that I can scale it down so that it fits in a max width/max height dimensions before uploading it.
I've even tried opening it in a sampled fashion, similar to what's mentioned here:
Strange out of memory issue while loading an image to a Bitmap object
However, with a complex webpage loaded in the WebView, I still get OutOfMemoryError when trying to open the image.
Is there a way to scale it, maybe using another process or something, that's more memory efficient?
I'm glad you asked, I was about to investigate this for my own project.
It looks like BitmapFactory.Options is your friend here, specifically BitmapFactory.Options.inSampleSize enter link description here. You can use BitmapFactory.decodeStream to get the image dimensions without creating a Bitmap.
Googling revealed the com.bristle.javalib.awt ImgUtil classes; these appear to be open source (don't know the license), and are AWT based, so may work on Android. The interesting method is ImgUtil.scalueImageToOutputStreamAsJPEG, which works with InputSteam/OutputStream, so may be memory efficient.
UPDATE
An alternative is to write a JNI wrapper around /system/lib/libjpeg.so, which appears to be standard on Android devices. This library works with scanlines, so can be memory friendly. Another plus is that using JNI should be faster than pure java.
Hope this helps,
Phil Lello
I had a similar problem and found a workable solution using BitmapFactory.Option.inScale. You can find details here: How do I scale a streaming bitmap in-place without reading the whole image first?