mm-4104, smart sharpen using opencl in adobe photoshop cc – challenges and achievements, by joseph...

SMART SHARPEN USING OPENCL IN PHOTOSHOP CC – CHALLENGES AND ACHIEVEMENTS

JOSEPH HSIEH ADOBE SYSTEMS INC.

2 | PRESENTATION TITLE | NOVEMBER 19, 2013 | CONFIDENTIAL

TOPICS

Table ‒ What is OpenCL? ‒ Why Adobe Photoshop CC chooses OpenCL? ‒ Smart Sharpen in Adobe Photoshop CC ‒ Challenges ‒ What have we learned? ‒ Demo ‒ Summary ‒ Q&A

What is OpenCL


WHAT IS OPENCL?

OpenCL is an open standard framework (supported by AMD, Apple, Intel, Nvidia, etc.) that allows developer to write programs that execute on different hardware platforms – GPUs, CPUs, DSPs, etc.

CUDA, GLSL, C++ AMP are competing GPGPU (General-Purpose Computing on Graphics Processing Units) technologies.

Why OpenCL


WHY ADOBE PHOTOSHOP CC CHOOSES OPENCL

Some advanced algorithms are just not fast enough.

GPU computing is suitable for algorithms that benefits from massive parallelization.

Cross-Platform (OpenCL and OpenGL Shading language (GLSL) are the only two cross-platform GPGPU solution).

Easier to map algorithm into OpenCL code than GLSL.

Highly efficient (capable of using fast cache memory).

Learning curves – Syntax (C99 plus vector support operations).

OpenCL is available on many latest mobile devices.

Smart Sharpen in Adobe Photoshop CC


SHARPENING

From Scott Kelby, “I haven’t met a digital camera (or scanned) photo that I didn’t think needed a little sharpening”.

For very blurred image, you need to do deblur, not the sharpening.


RENOVATED ADOBE PHOTOSHOP CC SMART SHARPEN FEATURE

Adobe renovated the legacy smart sharpen to ‒ Addresses “noise get boosted when you sharpen” issue. ‒ Better overall quality (preserve color). ‒ Reduce the halo effect.


COMPARISON BETWEEN LEGACY AND CURRENT SMART SHARPEN


COMPARISON BETWEEN LEGACY (ACCURATE) AND CURRENT VERSION


COMPARISON BETWEEN UNSHARP MASK AND SMART SHARPEN


COMPARISON BETWEEN UNSHARP MASK THRESHOLD AND SMART SHARPEN


SHARPENING TIPS

Sharpen the image on a separate layer.

Blending Mode: luminosity

Adjust opaque percentage

You may want to denoise before sharpening.


PERFORMANCE CONCERN

User experience – responsiveness is important. ‒ CPU Optimization.

‒ Multi-threading ‒ Vectorization using intrinsic instructions

Still not fast enough… ‒ Is the algorithm parallelizable? ‒ Is GPGPU Optimization suitable for our sharpening algorithm?


CHALLENGES IN SMART SHARPEN OPENCL DEVELOPMENT

Need to rethink about the algorithm.

Limited resources. (global memory, local memory, and private memory)

Algorithm is memory bound.

Avoid memory corruption.

Debug strategy.

How to make solid OpenCL kernels?

Optimization strategy.

Driver Issues? (better re-check the OpenCL spec and your kernel first…).

Quality control (GPU on different vendor platforms).


WHAT WE HAVE LEARNED

Reference code first (making sure you know the algorithm right).

Divide and conquer (easy to verify).

Always design for easy to do unit testing.



Optimization strategies (general practices): ‒ Always profile first. ‒ Algorithm parallelization. ‒ Global memory read as less as possible. (???) ‒ Memory access pattern. ‒ Avoid branching. ‒ Avoid edge condition handling. ‒ Arithmetic complexity (% is bad). ‒ Avoid bank conflict as much as possible. (???) ‒ Maximize the lazy synchronization. ‒ Trade-offs. ‒ Do not make the conclusion before doing the experiments… ‒ Optimization for certain vendor devices?



Quality control across various GPUs. ‒ Design of testing scenarios. ‒ Automation ‒ Collaborate with vendors.


SMART SHARPEN BENCHMARK ON 5616X3744 (21 MEGA) PIXELS IMAGE

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AMD Radeon 7970 i7-3770K 3.5GHz

Radius 64Radius 4Radius 1

In seconds

AMD CodeXL


AMD CODEXL – TOOL FOR HETEROGENEOUS COMPUTING

Features: ‒ OpenCL debug ‒ GPU profiling ‒ Analyze OpenCL kernel ‒ Collect OpenCL application trace ‒ Integrated with Microsoft Visual Studio


BENEFIT OF USING AMD CODEXL

Helps you to optimize your OpenCL kernel efficiently. ‒ Analyze the usage of VGPR, SGPR, Local Memory, etc. ‒ Profiling. ‒ Host code efficiency.


AMD CODEXL- OPENCL KERNEL DEBUG


AMD CODEXL- MEMORY OBJECT VIEWER


AMD CODEXL – TIMELINE VISUALIZATION Visualize host code execution, data transfer, and kernel execution.


AMD CODEXL – PERFORMANCE COUNTER


AMD CODEXL – KERNEL OCCUPANCY VIEWER

OpenCL 2.0


OPENCL 2.0 NEW FEATURES

Shared virtual memory ‒ Great for APUs and integrated GPUs.

Image2D, Image3D memory object read_write modifier.

Dynamic Parallelism: kernel can enqueue other kernels. ‒ Avoid to transfer execution and data between the device and host.

Pipe ‒ FIFO memory object.

Smart Sharpen Demo

Summary


SUMMARY

Adobe Photoshop CC adopts OpenCL to accelerate great features.

Adobe dedicates to deliver the best user experience. ‒ Embrace advanced solid technologies. ‒ Works closely with vendors to insure fully tested high quality software.

Thank You


DISCLAIMER & ATTRIBUTION

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ATTRIBUTION

© 2013 Advanced Micro Devices, Inc. All rights reserved. AMD, the AMD Arrow logo and combinations thereof are trademarks of Advanced Micro Devices, Inc. in the United States and/or other jurisdictions. SPEC is a registered trademark of the Standard Performance Evaluation Corporation (SPEC). Other names are for informational purposes only and may be trademarks of their respective owners.

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