Fast Bitmap Blur For Android SDK

android

bitmap

performance

optimization

byAnton Shumikhin·Sep 10, 2024

To apply a highly efficient blur on a bitmap for Android, opt for the RenderScript framework and its ScriptIntrinsicBlur class. Here's a trimmed down version of the ritual:

RenderScript rs = RenderScript.create(context);
Allocation alloc = Allocation.createFromBitmap(rs, bitmap);
ScriptIntrinsicBlur blur = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
blur.setRadius(blurRadius); // Keep calm and blur on! (0-25 values)
blur.setInput(alloc);
blur.forEach(alloc);
alloc.copyTo(bitmap);
alloc.destroy(); blur.destroy(); rs.destroy();

Note that blurRadius is limited to 25—this is your adjustment knob for blur intensity. This method dances with native processing and economizes system resources, making it ideal for real-time concertos.

Powerful blur methods

Algorithm selection: Faster than a caffeinated coder!

Quasimondo's Fast Blur algorithm is the cool hybrid of box blur speed and gaussian blur visual finesse. A whizz kid that's 7x faster than the gaussian blur. Performance shoots up, especially on those devices still nostalgic for the Jurassic age.

Resource gymnastics during the blur routine

Working with bitmaps is like juggling with nitro glycerine—You need to conserve memory. The Bitmap.createScaledBitmap comes handy with a true filter parameter, creating a smaller, yet tac sharp clone of your image. To keep the garbage collection ogre away, reuse Bitmap objects by employing inBitmap technique in BitmapFactory.Options.

NDK and JNI: When Java needs a native hand

Switch gears with Android NDK (Native Development Kit). When ascended to the NDK realm, blurring algorithms return with a blazing performance upgrade. Unleash the power of JNI (Java Native Interface) to summon these native operations where NDK rituals shun the Java layer, resulting in a speedier execution.

Tailoring your blur juice

Color stack maneuver: Your blur quality ally

Employ the dynamic color stack of Quasimondo's algorithm to micro-manage the blur quality. This guarantees the blur effect stays in harmony across the image, preserving a pleasing visual when under heavy blur.

Fine-tuning RenderScript: Your blur mixer

With ScriptIntrinsicBlur, dial blurRadius to tinker with blur intensities. Remember, more number, more blur. Resize the allocation to strike the perfect blend of blur quality and processing speed.

Advanced techniques and factors to consider

Progressive loading: The early bird

To gift your app a quick load, use BitmapFactory.Options' inSampleSize to load a scaled down version of your Bitmap. A smaller footprint means less memory and faster initial render.

Cutting down garbage collection: The memory miser

During bitmap operations, stake your memory dollars on variable reuse as far as possible. The pesky garbage collection comes along less often, avoiding jitters in animations or interactions.

Smooth transition effects: A performance in itself

To enhance the user experience, apply alpha fading between ImageViews. This ensures a seamless transition effect when blurring images.

Memory management: Every byte counts!

During blurring, the RGB_565 config can be the memory miser when high color fidelity is not a top priority. This halving of memory gives birth to a more efficient blur mechanism.

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