How to programmatically change contrast of a bitmap in android?
Solution 1
Try this. Your code didn't work because you create only a mutable bitmap and didn't copy the image of source bitmap to the mutable one if i'm not mistaken.
Hope It helps :)
private Bitmap adjustedContrast(Bitmap src, double value)
{
// image size
int width = src.getWidth();
int height = src.getHeight();
// create output bitmap
// create a mutable empty bitmap
Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig());
// create a canvas so that we can draw the bmOut Bitmap from source bitmap
Canvas c = new Canvas();
c.setBitmap(bmOut);
// draw bitmap to bmOut from src bitmap so we can modify it
c.drawBitmap(src, 0, 0, new Paint(Color.BLACK));
// color information
int A, R, G, B;
int pixel;
// get contrast value
double contrast = Math.pow((100 + value) / 100, 2);
// scan through all pixels
for(int x = 0; x < width; ++x) {
for(int y = 0; y < height; ++y) {
// get pixel color
pixel = src.getPixel(x, y);
A = Color.alpha(pixel);
// apply filter contrast for every channel R, G, B
R = Color.red(pixel);
R = (int)(((((R / 255.0) - 0.5) * contrast) + 0.5) * 255.0);
if(R < 0) { R = 0; }
else if(R > 255) { R = 255; }
G = Color.green(pixel);
G = (int)(((((G / 255.0) - 0.5) * contrast) + 0.5) * 255.0);
if(G < 0) { G = 0; }
else if(G > 255) { G = 255; }
B = Color.blue(pixel);
B = (int)(((((B / 255.0) - 0.5) * contrast) + 0.5) * 255.0);
if(B < 0) { B = 0; }
else if(B > 255) { B = 255; }
// set new pixel color to output bitmap
bmOut.setPixel(x, y, Color.argb(A, R, G, B));
}
}
return bmOut;
}
Solution 2
Here is complete method:
/**
*
* @param bmp input bitmap
* @param contrast 0..10 1 is default
* @param brightness -255..255 0 is default
* @return new bitmap
*/
public static Bitmap changeBitmapContrastBrightness(Bitmap bmp, float contrast, float brightness)
{
ColorMatrix cm = new ColorMatrix(new float[]
{
contrast, 0, 0, 0, brightness,
0, contrast, 0, 0, brightness,
0, 0, contrast, 0, brightness,
0, 0, 0, 1, 0
});
Bitmap ret = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());
Canvas canvas = new Canvas(ret);
Paint paint = new Paint();
paint.setColorFilter(new ColorMatrixColorFilter(cm));
canvas.drawBitmap(bmp, 0, 0, paint);
return ret;
}
Solution 3
We can use seek bar
to adjust contrast.
MainActivity.java:
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.Paint;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
ImageView imageView;
SeekBar seekbar;
TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageView = (ImageView) findViewById(R.id.image);
textView = (TextView) findViewById(R.id.label);
seekbar = (SeekBar) findViewById(R.id.seekbar);
seekbar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean b) {
imageView.setImageBitmap(changeBitmapContrastBrightness(BitmapFactory.decodeResource(getResources(), R.drawable.lhota), (float) progress / 100f, 1));
textView.setText("Contrast: "+(float) progress / 100f);
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {}
});
seekbar.setMax(200);
seekbar.setProgress(100);
}
public static Bitmap changeBitmapContrastBrightness(Bitmap bmp, float contrast, float brightness) {
ColorMatrix cm = new ColorMatrix(new float[]
{
contrast, 0, 0, 0, brightness,
0, contrast, 0, 0, brightness,
0, 0, contrast, 0, brightness,
0, 0, 0, 1, 0
});
Bitmap ret = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());
Canvas canvas = new Canvas(ret);
Paint paint = new Paint();
paint.setColorFilter(new ColorMatrixColorFilter(cm));
canvas.drawBitmap(bmp, 0, 0, paint);
return ret;
}
}
activity_main.java:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ImageView
android:id="@+id/image"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/label"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="8dp"
android:textAppearance="@android:style/TextAppearance.Holo.Medium" />
<SeekBar
android:id="@+id/seekbar"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
Solution 4
Here is a Renderscript implementation (from the Gradle Example Projects)
ip.rsh
#pragma version(1)
#pragma rs java_package_name(your.app.package)
contrast.rs
#include "ip.rsh"
static float brightM = 0.f;
static float brightC = 0.f;
void setBright(float v) {
brightM = pow(2.f, v / 100.f);
brightC = 127.f - brightM * 127.f;
}
void contrast(const uchar4 *in, uchar4 *out)
{
#if 0
out->r = rsClamp((int)(brightM * in->r + brightC), 0, 255);
out->g = rsClamp((int)(brightM * in->g + brightC), 0, 255);
out->b = rsClamp((int)(brightM * in->b + brightC), 0, 255);
#else
float3 v = convert_float3(in->rgb) * brightM + brightC;
out->rgb = convert_uchar3(clamp(v, 0.f, 255.f));
#endif
}
Java
private Bitmap changeBrightness(Bitmap original RenderScript rs) {
Allocation input = Allocation.createFromBitmap(rs, original);
final Allocation output = Allocation.createTyped(rs, input.getType());
ScriptC_contrast mScript = new ScriptC_contrast(rs);
mScript.invoke_setBright(50.f);
mScript.forEach_contrast(input, output);
output.copyTo(original);
return original;
}
Solution 5
Assumption - ImageView is used to display the bitmap
I did a more enhancement in the Ruslan's answer
Instead of replacing bitmap every time (which makes it slow if you are using seek bar) we can work on the Color Filter of the ImageView.
float contrast;
float brightness = 0;
ImageView imageView;
// SeekBar ranges from 0 to 90
// contrast ranges from 1 to 10
mSeekBarContrast.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
contrast = (float) (i + 10) / 10;
// Changing the contrast of the bitmap
imageView.setColorFilter(getContrastBrightnessFilter(contrast,brightness));
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
ColorMatrixColorFilter getContrastBrightnessFilter(float contrast, float brightness) {
ColorMatrix cm = new ColorMatrix(new float[]
{
contrast, 0, 0, 0, brightness,
0, contrast, 0, 0, brightness,
0, 0, contrast, 0, brightness,
0, 0, 0, 1, 0
});
return new ColorMatrixColorFilter(cm);
}
P.S - Brightness can also be changed along with contrast using this method
Comments
-
Sanchit Paurush about 4 years
I want to programmatically change the contrast of bitmap. Till now I have tried this.
private Bitmap adjustedContrast(Bitmap src, double value) { // image size int width = src.getWidth(); int height = src.getHeight(); // create output bitmap Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig()); // color information int A, R, G, B; int pixel; // get contrast value double contrast = Math.pow((100 + value) / 100, 2); // scan through all pixels for(int x = 0; x < width; ++x) { for(int y = 0; y < height; ++y) { // get pixel color pixel = src.getPixel(x, y); A = Color.alpha(pixel); // apply filter contrast for every channel R, G, B R = Color.red(pixel); R = (int)(((((R / 255.0) - 0.5) * contrast) + 0.5) * 255.0); if(R < 0) { R = 0; } else if(R > 255) { R = 255; } G = Color.green(pixel); G = (int)(((((G / 255.0) - 0.5) * contrast) + 0.5) * 255.0); if(G < 0) { G = 0; } else if(G > 255) { G = 255; } B = Color.blue(pixel); B = (int)(((((B / 255.0) - 0.5) * contrast) + 0.5) * 255.0); if(B < 0) { B = 0; } else if(B > 255) { B = 255; } // set new pixel color to output bitmap bmOut.setPixel(x, y, Color.argb(A, R, G, B)); } } return bmOut; }
But this does not work as expected. Please help me in this or provide any other solution to achieve this. Thanks in advance.
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devsnd over 11 yearswhat doesn't work as expected? please elaborate more detailed what does work and what doesnt.
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Sanchit Paurush over 11 yearsThanks for your reply. I tried this. But this code works with canvas only and I cannot retrieve the changed image from canvas. So is there any other way for it.
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kdroider over 11 yearsI edited the link above. I hope that will be more helpful in your case. :)
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Sanchit Paurush over 11 yearsIt is the same code that I gave above. It always make my image black and white and does not make it back to its original colors. Please provide any other.
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Aron Lorincz over 10 yearsThis's the fastest solution I found so far. Probably only a renderscript-based one would be faster...
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Gusten over 10 yearsAwesome, this method processes my image in about a second, above method took about 20 seconds.
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mnsalim about 10 yearswhat is the max & min value of contrast & brightness. I use -255 t0 255 for brightness & -100 to 100 for contrast, but i get wrong result. I also try to use value 0 for contrast while some value for brightness i get a black image.Please help me. I got this is the fastest method, but it give me wrong result, definitely i do something wrong, it would be nice if any one correct me.
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Vasiliy Kulakov over 9 yearsThanks, but I don't think we need a
Canvas
here -- we're writing to the bitmapbmOut
directly. -
vianna77 over 8 yearsJust a improvement to the code due to the constant break on the bmp.getConfig... Bitmap.Config config = src.getConfig(); if (config == null) { config = Bitmap.Config.ARGB_8888; } Bitmap ret = Bitmap.createBitmap(src.getWidth(), src.getHeight(), config);
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Andrew F over 8 yearsCan you post more completed example?
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Patrick over 8 yearsthe sample is pretty complete, for integrating it see the link, bottom of the page with full projects
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Andrew F over 8 yearsanyway can you post direct link to full project? :) I found only one link and it's unavailable
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Patrick over 8 yearsThey seem to have removed the link to the projects, just search how to create an app with renderscript, the rest should be clear
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V I J E S H almost 7 yearsThis will create OutOfMemmory if we are changing the brightness through silder
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Kishan Donga almost 4 yearswhat is max and min values can update your answer with this values
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M DEV almost 2 yearsThis is best method to make contrast and brightness to the image. It works faster then other tools. Thank you so much
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M DEV almost 2 yearsnow, it is working very fine. If we seek back from 50 then the image gets dark and if we seek more from 50 then image gets bright.