Develop Reference

What is the fastest way to compress image to a specified size?

In my project, I need to upload some images(1-10) to server sometimes. The size varies from 1M to 10M. Before upload,each image should be compressed until size<512KB. I do the compression like this:
public static byte[] compressImageA(Bitmap image, int maxSize) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int options = 100;
image.compress(Bitmap.CompressFormat.JPEG, options, baos);
while (baos.size() / 1024 > maxSize) {
baos.reset();
options -= 10;
image.compress(Bitmap.CompressFormat.JPEG, options, baos);
}
if (image != null && !image.isRecycled()) {
try {
image.recycle();
} catch (Exception e) {
}
}
return baos.toByteArray();
}
This method can make it, but not fast enough.For example,it takes about 25 seconds to compress 10 images.(Size of each is between 1M and 10M).After some tests,I find Bitmap.compress() may be called many times and takes the most time during a compression.So what can I do to make it faster? I want Bitmap.compress() to be called only 1 time during each compression.Or is there any other way to compress image to a specified size more faster？

You can use this method to reduce size from actual size
/**
* reduces the size of the image
*
* #param image uncompressed image
* #param reduce how much to reduce
* #return new bitmap
*/
public static Bitmap reduceBitmap(Bitmap image, int reduce) {
int width = image.getWidth();
int height = image.getHeight();
float bitmapRatio = (float) width / (float) height;
if (bitmapRatio > 1) {
width -= reduce;
height = (int) (width / bitmapRatio);
} else {
height -= reduce;
width = (int) (height * bitmapRatio);
}
if (width > 0 && height > 0)
return Bitmap.createScaledBitmap(image, width, height, true);
else
return image;
}
or You can use below codes according to your need, I am using it for PNG your can check for other
Bitmap actualImage=BitmapFactory.decodeStream(getAssets().open("imagg1.png"));
ByteArrayOutputStream out = new ByteArrayOutputStream();
actualImage.compress(Bitmap.CompressFormat.PNG, 100, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

Your algorithm is about as fast as it gets.
Time to start thinking outside the box. 10 images in 25s means 1 image takes 2.5s. How fast do you want it to be? Luckily, the algorithm is easily parallelizable. So you could split the task across n computers.

How to reduce image size into 1MB

I want my application to upload image with no size limit, but in the code, I want to resize the image into 1MB if the image size exceeds. I have tried many ways but I couldn't find any code for the requirement I have mentioned above.
For once, I have tried this:
public void scaleDown() {
int width = stdImageBmp.getWidth();
int height = stdImageBmp.getHeight();
Matrix matrix = new Matrix();
float scaleWidth = ((float) MAX_WIDTH) / width;
float scaleHeight = ((float) MAX_HEIGHT) / height;
matrix.postScale(scaleWidth, scaleHeight);
stdImageBmp = Bitmap.createBitmap(stdImageBmp, 0, 0, width, height, matrix, true);
File Image = new File("path");
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
//compress bmp
stdImageBmp.compress(Bitmap.CompressFormat.JPEG, 100, byteArrayOutputStream);
byte[] byteArray = byteArrayOutputStream.toByteArray();
imgViewStd.setImageBitmap(stdImageBmp);
Log.d("resizedBitmap", stdImageBmp.toString());
width = stdImageBmp.getWidth();
height = stdImageBmp.getHeight();
System.out.println("imgWidth" + width);
System.out.println("imgHeight" + height);
}

you can use this code to resize a bitmap and for image size < 1MB i recommend use resolution of 480x640
public Bitmap getResizedBitmap(Bitmap bm, int newWidth, int newHeight) {
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// "RECREATE" THE NEW BITMAP
return Bitmap.createBitmap(
bm, 0, 0, width, height, matrix, false);
}

If you really want the Bitmap that scales down to the Bitmap that is the closest to a given amount of bytes, heres the method I use. (It does not uses a while loop)
NOTE: This method only works if passed bitmap is in ARGB_8888 configuration.
See: Compress bitmap to a specific byte size in Android for the conversion method.
/**
* Method to scale the Bitmap to respect the max bytes
*
* #param input the Bitmap to scale if too large
* #param maxBytes the amount of bytes the Image may be
* #return The scaled bitmap or the input if already valid
* #Note: The caller of this function is responsible for recycling once the input is no longer needed
*/
public static Bitmap scaleBitmap(final Bitmap input, final long maxBytes) {
final int currentWidth = input.getWidth();
final int currentHeight = input.getHeight();
final int currentPixels = currentWidth * currentHeight;
// Get the amount of max pixels:
// 1 pixel = 4 bytes (R, G, B, A)
final long maxPixels = maxBytes / 4; // Floored
if (currentPixels <= maxPixels) {
// Already correct size:
return input;
}
// Scaling factor when maintaining aspect ratio is the square root since x and y have a relation:
final double scaleFactor = Math.sqrt(maxPixels / (double) currentPixels);
final int newWidthPx = (int) Math.floor(currentWidth * scaleFactor);
final int newHeightPx = (int) Math.floor(currentHeight * scaleFactor);
Timber.i("Scaled bitmap sizes are %1$s x %2$s when original sizes are %3$s x %4$s and currentPixels %5$s and maxPixels %6$s and scaled total pixels are: %7$s",
newWidthPx, newHeightPx, currentWidth, currentHeight, currentPixels, maxPixels, (newWidthPx * newHeightPx));
final Bitmap output = Bitmap.createScaledBitmap(input, newWidthPx, newHeightPx, true);
return output;
}
Where the Sample use would look something like:
// (1 MB)
final long maxBytes = 1024 * 1024;
// Scale it
final Bitmap scaledBitmap = BitmapUtils.scaleBitmap(yourBitmap, maxBytes);
if(scaledBitmap != yourBitmap){
// Recycle the bitmap since we can use the scaled variant:
yourBitmap.recycle();
}
// ... do something with the scaled bitmap

I've tried to comment it but the comment become too big.
So, I've tested many solutions and it seems like there are only TWO solutions for this problem, which give some results.
Lets discuss Koen solution first. What it actually does is creates a scaled JPG
Bitmap.createScaledBitmap(input, newWidthPx, newHeightPx, true)
Seems like it does not compress it at all but just cuts off the resolution.
I've tested this code and when I pass MAX_IMAGE_SIZE = 1024000 it gives me 350kb compressed image out of 2.33Mb original image. Bug?
Also it lacks quality. I was unable to recognize a text on A4 sheet of paper photo made by Google Pixel.
There is another solution to this problem, which gives good quality, but lacks in speed.
A WHILE LOOP!
Basically you just loop through image size, until you get the desired size
private fun scaleBitmap() {
if (originalFile.length() > MAX_IMAGE_SIZE) {
var streamLength = MAX_IMAGE_SIZE
var compressQuality = 100
val bmpStream = ByteArrayOutputStream()
while (streamLength >= MAX_IMAGE_SIZE) {
bmpStream.use {
it.flush()
it.reset()
}
compressQuality -= 8
val bitmap = BitmapFactory.decodeFile(originalFile.absolutePath, BitmapFactory.Options())
bitmap.compress(Bitmap.CompressFormat.JPEG, compressQuality, bmpStream)
streamLength = bmpStream.toByteArray().size
}
FileOutputStream(compressedFile).use {
it.write(bmpStream.toByteArray())
}
}
}
I think that this approach will consume exponential time depending on image resolution.
9mb image takes up to 12 seconds to compress down to 1mb.
Quality is good.
You can tweak this by reducing the original bitmap resolution(which seems like a constant operation), by doing:
options.inSampleSize = 2;
What we need to do is to somehow calculate compressQuality for any image.
There should be a math around this, so we can determinate compressQuality from original image size or width + height.

Loading big image to bitmap in android

Hi i am using below code to load images from sdcard, it is running correctly,
Bitmap picture=BitmapFactory.decodeFile("/sdcard...");
or
Bitmap picture= BitmapFactory.decodeByteArray(byte[]..);
The byte[] array contains bytes read from sdcard by using FileInputstream and is not null. Both of above codes work fine. The problem is that they dont work for images that are larger e.g. i have an image of 1.8 mb in size. My app crashes while decoding the image. Any method used for larges image fails.
Any solution plz thakns.

Try to create purgeable Bitmap.
byte[] data = ...(read byte array from file)
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inPurgeable = true;
Bitmap picture = BitmapFactory.decodeByteArray(data, 0, data.length, opt);

Use the below code to resize the image any size you need..
Bitmap picture=BitmapFactory.decodeFile("/sdcard...");
int width = picture.getWidth();
int height = picture.getWidth();
float aspectRatio = (float) width / (float) height;
int newWidth = 70;
int newHeight = (int) (70 / aspectRatio);
picture= Bitmap.createScaledBitmap(picture, newWidth, newHeight, true);

The tutorial at http://developer.android.com/training/displaying-bitmaps/load-bitmap.html explains how to load large images into a Bitmap without encountering the dreaded OutOfMemoryException.

The Android VM has memory limitation which limits the size of the images decodable. To display the resixed images in an image view the following code could be used.
decode_options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(temp,decode_options); //This will just fill the output parameters
if(decode_options.outWidth > image_width
|| decode_options.outHeight > image_height)
{
float scale_width,scale_height;
scale_width = ((float)decode_options.outWidth) / image_width;
scale_param = scale_width;
scale_height = ((float)decode_options.outHeight) / image_height;
if(scale_param < scale_height)
scale_param = scale_height;
}
decode_options.inJustDecodeBounds = false;
decode_options.inSampleSize = (int)(scale_param + 1);
decode_options.inPreferredConfig = Bitmap.Config.ARGB_8888;
decoded_data =
BitmapFactory.decodeFile(temp,decode_options);

Proportionally resize a bitmap

I've got a bitmap... and if the bitmap's height is greater than maxHeight, or the width is greater than maxWidth, I'd like to proportionally resize the image so that it fits in maxWidth X maxHeight. Here's what I'm trying:
BitmapDrawable bmp = new BitmapDrawable(getResources(), PHOTO_PATH);
int width = bmp.getIntrinsicWidth();
int height = bmp.getIntrinsicHeight();
float ratio = (float)width/(float)height;
float scaleWidth = width;
float scaleHeight = height;
if((float)mMaxWidth/(float)mMaxHeight > ratio) {
scaleWidth = (float)mMaxHeight * ratio;
}
else {
scaleHeight = (float)mMaxWidth / ratio;
}
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap out = Bitmap.createBitmap(bmp.getBitmap(),
0, 0, width, height, matrix, true);
try {
out.compress(Bitmap.CompressFormat.JPEG, 100,
new FileOutputStream(PHOTO_PATH));
}
catch(FileNotFoundException fnfe) {
fnfe.printStackTrace();
}
I get the following exception:
java.lang.IllegalArgumentException: bitmap size exceeds 32bits
What am I doing wrong here?

Your scaleWidth and scaleHeight should be scale factors (so not very big numbers) but your code seems to pass in the actual width and height you're looking for. So you're ending up massively increasing the size of your bitmap.
I think there are other problems with the code to derive scaleWidth and scaleHeight as well though. For one thing your code always has either scaleWidth = width or scaleHeight = height, and changes only one of them, so you're going to be distorting the aspect ratio of your image as well. If you just want to resize the image then you should just have a single scaleFactor.
Also, why does your if statement check for, effectively, maxRatio > ratio ? Shouldn't you be checking for width > maxWidth or height > maxHeight?

This is because the value of scaleWidth or scaleHeight is too large,scaleWidth or scaleHeight is mean enlarge or shrink 's rate,but not width or height,too large rate lead to bitmap size exceeds 32 bits
matrix.postScale(scaleWidth, scaleHeight);

this is how i did it:
public Bitmap decodeAbtoBm(byte[] b){
Bitmap bm; // prepare object to return
// clear system and runtime of rubbish
System.gc();
Runtime.getRuntime().gc();
//Decode image size only
BitmapFactory.Options oo = new BitmapFactory.Options();
// only decodes size, not the whole image
// See Android documentation for more info.
oo.inJustDecodeBounds = true;
BitmapFactory.decodeByteArray(b, 0, b.length ,oo);
//The new size we want to scale to
final int REQUIRED_SIZE=200;
// Important function to resize proportionally.
//Find the correct scale value. It should be the power of 2.
int scale=1;
while(oo.outWidth/scale/2>=REQUIRED_SIZE
&& oo.outHeight/scale/2>=REQUIRED_SIZE)
scale*=2; // Actual scaler
//Decode Options: byte array image with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize=scale; // set scaler
o2.inPurgeable = true; // for effeciency
o2.inInputShareable = true;
// Do actual decoding, this takes up resources and could crash
// your app if you do not do it properly
bm = BitmapFactory.decodeByteArray(b, 0, b.length,o2);
// Just to be safe, clear system and runtime of rubbish again!
System.gc();
Runtime.getRuntime().gc();
return bm; // return Bitmap to the method that called it
}

Android how to create runtime thumbnail

I have a large sized image. At runtime, I want to read the image from storage and scale it so that its weight and size gets reduced and I can use it as a thumbnail. When a user clicks on the thumbnail, I want to display the full-sized image.

Try this
Bitmap ThumbImage = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(imagePath), THUMBSIZE, THUMBSIZE);
This Utility is available from API_LEVEl 8. [Source]

My Solution
byte[] imageData = null;
try
{
final int THUMBNAIL_SIZE = 64;
FileInputStream fis = new FileInputStream(fileName);
Bitmap imageBitmap = BitmapFactory.decodeStream(fis);
imageBitmap = Bitmap.createScaledBitmap(imageBitmap, THUMBNAIL_SIZE, THUMBNAIL_SIZE, false);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
imageBitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
imageData = baos.toByteArray();
}
catch(Exception ex) {
}

The best solution I found is the following. Compared with the other solutions this one does not need to load the full image for creating a thumbnail, so it is more efficient!
Its limit is that you can not have a thumbnail with exact width and height but the solution as near as possible.
File file = ...; // the image file
Options bitmapOptions = new Options();
bitmapOptions.inJustDecodeBounds = true; // obtain the size of the image, without loading it in memory
BitmapFactory.decodeFile(file.getAbsolutePath(), bitmapOptions);
// find the best scaling factor for the desired dimensions
int desiredWidth = 400;
int desiredHeight = 300;
float widthScale = (float)bitmapOptions.outWidth/desiredWidth;
float heightScale = (float)bitmapOptions.outHeight/desiredHeight;
float scale = Math.min(widthScale, heightScale);
int sampleSize = 1;
while (sampleSize < scale) {
sampleSize *= 2;
}
bitmapOptions.inSampleSize = sampleSize; // this value must be a power of 2,
// this is why you can not have an image scaled as you would like
bitmapOptions.inJustDecodeBounds = false; // now we want to load the image
// Let's load just the part of the image necessary for creating the thumbnail, not the whole image
Bitmap thumbnail = BitmapFactory.decodeFile(file.getAbsolutePath(), bitmapOptions);
// Save the thumbnail
File thumbnailFile = ...;
FileOutputStream fos = new FileOutputStream(thumbnailFile);
thumbnail.compress(Bitmap.CompressFormat.JPEG, 90, fos);
fos.flush();
fos.close();
// Use the thumbail on an ImageView or recycle it!
thumbnail.recycle();

Here is a more complete solution to scaling down a Bitmap to thumbnail size. It expands on the Bitmap.createScaledBitmap solution by maintaining the aspect ratio of the images and also padding them to the same width so that they look good in a ListView.
Also, it would be best to do this scaling once and store the resulting Bitmap as a blob in your Sqlite database. I have included a snippet on how to convert the Bitmap to a byte array for this purpose.
public static final int THUMBNAIL_HEIGHT = 48;
public static final int THUMBNAIL_WIDTH = 66;
imageBitmap = BitmapFactory.decodeByteArray(mImageData, 0, mImageData.length);
Float width = new Float(imageBitmap.getWidth());
Float height = new Float(imageBitmap.getHeight());
Float ratio = width/height;
imageBitmap = Bitmap.createScaledBitmap(imageBitmap, (int)(THUMBNAIL_HEIGHT*ratio), THUMBNAIL_HEIGHT, false);
int padding = (THUMBNAIL_WIDTH - imageBitmap.getWidth())/2;
imageView.setPadding(padding, 0, padding, 0);
imageView.setImageBitmap(imageBitmap);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
imageBitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
byte[] byteArray = baos.toByteArray();

Use BitmapFactory.decodeFile(...) to get your Bitmap object and set it to an ImageView with ImageView.setImageBitmap().
On the ImageView set the layout dimensions to something small, eg:
android:layout_width="66dip" android:layout_height="48dip"
Add an onClickListener to the ImageView and launch a new activity, where you display the image in full size with
android:layout_width="wrap_content" android:layout_height="wrap_content"
or specify some larger size.

/**
* Creates a centered bitmap of the desired size.
*
* #param source original bitmap source
* #param width targeted width
* #param height targeted height
* #param options options used during thumbnail extraction
*/
public static Bitmap extractThumbnail(
Bitmap source, int width, int height, int options) {
if (source == null) {
return null;
}
float scale;
if (source.getWidth() < source.getHeight()) {
scale = width / (float) source.getWidth();
} else {
scale = height / (float) source.getHeight();
}
Matrix matrix = new Matrix();
matrix.setScale(scale, scale);
Bitmap thumbnail = transform(matrix, source, width, height,
OPTIONS_SCALE_UP | options);
return thumbnail;
}

I found an easy way to do this
Bitmap thumbnail = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(mPath),200,200)
Syntax
Bitmap thumbnail = ThumbnailUtils.extractThumbnail(Bitmap source,int width,int height)
OR
use Picasso dependancy
compile 'com.squareup.picasso:picasso:2.5.2'
Picasso.with(context)
.load("file:///android_asset/DvpvklR.png")
.resize(50, 50)
.into(imageView2);
Reference Picasso

If you want high quality result, so use [RapidDecoder][1] library. It is simple as follow:
import rapid.decoder.BitmapDecoder;
...
Bitmap bitmap = BitmapDecoder.from(getResources(), R.drawable.image)
.scale(width, height)
.useBuiltInDecoder(true)
.decode();
Don't forget to use builtin decoder if you want to scale down less than 50% and a HQ result.

This answer is based on the solution presented in https://developer.android.com/topic/performance/graphics/load-bitmap.html (without using of external libraries) with some changes by me to make its functionality better and more practical.
Some notes about this solution:
It is assumed that you want to keep the aspect ratio. In other words:
finalWidth / finalHeight == sourceBitmap.getWidth() / sourceBitmap.getWidth() (Regardless of casting and rounding issues)
It is assumed that you have two values (maxWidth & maxHeight) that you want any of the dimensions of your final bitmap doesn't exceed its corresponding value. In other words:
finalWidth <= maxWidth && finalHeight <= maxHeight
So minRatio has been placed as the basis of calculations (See the implementation). UNLIKE the basic solution that has placed maxRatio as the basis of calculations in actual. Also, the calculation of inSampleSize has been so much better (more logic, brief and efficient).
It is assumed that you want to (at least) one of the final dimensions has exactly the value of its corresponding maxValue (each one was possible, by considering the above assumptions). In other words:
finalWidth == maxWidth || finalHeight == maxHeight
The final additional step in compare to the basic solution (Bitmap.createScaledBitmap(...)) is for this "exactly" constraint. The very important note is you shouldn't take this step at first (like the accepted answer), because of its significant consumption of memory in case of huge images!
It is for decoding a file. You can change it like the basic solution to decode a resource (or everything that BitmapFactory supports).
The implementation:
public static Bitmap decodeSampledBitmap(String pathName, int maxWidth, int maxHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(pathName, options);
final float wRatio_inv = (float) options.outWidth / maxWidth,
hRatio_inv = (float) options.outHeight / maxHeight; // Working with inverse ratios is more comfortable
final int finalW, finalH, minRatio_inv /* = max{Ratio_inv} */;
if (wRatio_inv > hRatio_inv) {
minRatio_inv = (int) wRatio_inv;
finalW = maxWidth;
finalH = Math.round(options.outHeight / wRatio_inv);
} else {
minRatio_inv = (int) hRatio_inv;
finalH = maxHeight;
finalW = Math.round(options.outWidth / hRatio_inv);
}
options.inSampleSize = pow2Ceil(minRatio_inv); // pow2Ceil: A utility function that comes later
options.inJustDecodeBounds = false; // Decode bitmap with inSampleSize set
return Bitmap.createScaledBitmap(BitmapFactory.decodeFile(pathName, options),
finalW, finalH, true);
}
/**
* #return the largest power of 2 that is smaller than or equal to number.
* WARNING: return {0b1000000...000} for ZERO input.
*/
public static int pow2Ceil(int number) {
return 1 << -(Integer.numberOfLeadingZeros(number) + 1); // is equivalent to:
// return Integer.rotateRight(1, Integer.numberOfLeadingZeros(number) + 1);
}
Sample Usage, in case of you have an imageView with a determined value for layout_width (match_parent or a explicit value) and a indeterminate value for layout_height (wrap_content) and instead a determined value for maxHeight:
imageView.setImageBitmap(decodeSampledBitmap(filePath,
imageView.getWidth(), imageView.getMaxHeight()));