In my android project I need to get access for each separate pixel of JPEG image. Image created by built-in photo application. I try to convert JPEG into Bitmap class instance, but OutOfMemoryException was thrown. After searching info about this problem I have found the following solution: resize image! But quality of image is important in my project, and i can't resize it. Is there any way to get each-pixel access?
if your image is too big and the quality is important i suppose the best way is to use or create your own class to cut the image in zone (eg : 50*50 px) , there is several jpeg info class in the internet to help you understand how work jpeg files.
Have you tried BufferedImage ? (it's not in the sdk but maybe usable)
The nature of jpeg makes it very hard to get the value of a single pixel. The main reason is that the data is not byte aligned, another is that everything is encoded in blocks that can be of sizes 8x16, 16x8 and 8x8. Also, you need to handle subsampling of chroma values.
If the image contains restart markers, maybe you can skip into the image so you don't have to decode the whole image before getting the pixel value.
Related
how to compress GIF image before upload it to the server ?, i tried some android libraries to compress gif image but it convert it to png image. is there any way to compress gif image ?
im using a bitmap in my projects.
Bitmap
Example code:
ImageView carView = (ImageView) v.findViewById(R.id.imagen_cr7);
byte[] decodedString = Base64.decode(picture, Base64.NO_WRAP);
InputStream input=new ByteArrayInputStream(decodedString);
Bitmap ext_pic = BitmapFactory.decodeStream(input);
carView.setImageBitmap(ext_pic);
GIF is a lossless image compression format: it is set up to reproduce the image exactly.
As a consequence, there is no "image quality" slider (as in JPEG encoders); although a GIF will likely be much smaller than an uncompressed format (such as many camera RAW or common TIFF options), there is a limit to how far it can go.
Also, you should know that GIF is limited to 8 bits per pixel (so it is most appropriate for line art, not photo-like images). If your source image is a full 24 bits, it must be dithered to fit into a 256-entry color palette. So, although the GIF format itself is lossless, the image processing required to use it in the first place may be lossy.
There are a number of things you can do to reduce the size of your image file:
You can choose a lossy format (such as JPEG), which will allow much greater compression. Note that JPEG works well on photo-like images, but not so well on line art. Also, (although your question explicitly rejects it) PNG may be a reasonable option, as it (losslessly) supports 24-bpp images.
As mentioned in a comment, you can try reducing the resolution of your image, and shipping the reduced version. If you can't generate a smaller image to start with, image resizing typically works well on photo-like images, and there are nonlinear resizing filters available that are specifically intended to handle line art.
If a full-resolution GIF is mandatory for your application, you may be able to generate an image that is more compressible by the GIF format. GIF compresses solid blocks of color extremely well -- but does less well on dithered or noisy images (such as you might get from converting a 24-bpp image to GIF format).
Since you have not given any information on your requirements (what kind of image you have, where you got it, and what you need it for), it is hard to come up with specific advice.
However, there is a good chance that your GIF has far more resolution than you need for your particular application (leading to option #2).
I want to use Big Size Image In Back Ground so How Can I do And i want to It's Working For All Device
As per your requirement, I guess that you are getting image from server end. Some time big size Bitmap throw OutOfMemoryException. So do one thing. Use this library to compress image and then show it to ImageView.
https://github.com/zetbaitsu/Compressor
You can also use Library. It provide you facility to fix image size and quality. so it won't be problem for you.
Nostra Image Loader
I am writing a Android app which need to display some high quality picture(took from professional DSLR). The problem is it can't be display from gallery.
I choose a photo in Gallery first. The target picture is 2464*1632 JPEG, roughly 4.5M;
Then I just need to compress it to 800*600 and display it in imageview:
image.setImageBitmap(this.bmp);
Thing is that I have tested other image I downloaded form internet(really low quality), and it works without any problem. Can anybody tell me why it can't be displayed? I will be really appericiated
Large images are tricky to handle due to limited memory. You have several choices:
Use a WebView (this allows you to have pinch and zoom functionality to make use of those extra pixels
Decode the image down to the size of the display and then put it in an ImageView using BitmapOpts http://developer.android.com/reference/android/graphics/BitmapFactory.Options.html and changing inSampleSize. It seems you may be having difficulty with that, so consider using createScaledBitmap which just needs the dest width and height.
I am using the Camera activity to capture the JPEG image. After image is saved and the controll is returned back to my application activity I would like to to determine the captured JPEG image dimensions without loading the whole image into memory via Bitmap object - can it be easily done somehow?
Is there any class, which reads the JPEG header and give me such information? I would like to avoid OOM conditions - but might be it is not a problem to load the whole image into memory - is it?
After knowing the dimensions I would like to use BitmapFactory to scale the image.
Thanks a lot
Kind Regards,
STeN
Perhaps a work-around (see 2nd approach) by setting the quality?
bmp.compress(CompressFormat.JPEG, 75,
pfos);
You would have to do a trial run to see what size the quality gets you though...
*The first approach creates a log file to get the width and height but not sure if you wanted the extra step of looking at a log file.
You can use the ExifInterface class to read the image width and height.
I'm working on an image processing application for Android that recognizes music notation from pictures taken of music sheets.
I tried to load the entire image into a Bitmap using the BitmapFactory.decodeFile(imgPath) method, but because my phone doesn't have enough memory I get a "VM heap size" error. To work around this, I'd like to chop the full image into smaller pieces, but I'm not sure how to do that.
I also saw that it was possible to reduce the memory size of the Bitmap by using the inSampleSize property of the BitmapFactory.Option class, but if I do that I won't get the high resolution image I need for the music notation recognition process.
Is there anyway to handle this without going to NDK?
Android 2.3.3 has a new API called android.graphics.BitmapRegionDecoder that lets you do exactly what you want.
You would for instance do the following:
BitmapRegionDecoder decoder = BitmapRegionDecoder.newInstance(myStream, false);
Bitmap region = decoder.decodeRegion(new Rect(10, 10, 50, 50), null);
Easy :)
If it's from a camera the image will likely be jpeg format. You could use an external jpeg library - either in java or via the NDK, whatever you can find - to give you better control and load it a piece at a time. If you need it as an android.graphics.Bitmap then I suspect you will then need to re-encode the subimage as PNG or JPEG and pass it to BitmapFactory.decodeByteArray(). (If memory is a concern then do be sure to forget your references to the pieces of the bitmap promptly so that the garbage collector can run effectively.)
The same technique will also work if the input graphic is PNG format, or just about anything else provided you can find suitable decode code for it.
I think that by loading the image piecewise you are setting yourself an algorithmic challenge in deciding what parts of it you are really interested in the full detail of. I notice that BitmapFactory.Options includes the option to subsample, that might be useful if you want to analyse an overview of the image to decide what regions to load in full detail.
If you're dealing with JPEG images, see my answer to this question as well as this example.
I don't know how possible it is to get libijg on Android, but if it is, then it's worth a shot.