Would it be a problem for you if I rewrite the opencl engine completely,
and you people provide me help to link the tesseract kernel -> opencl
engine parts?
in attachment, I already have a list of features I'd like to port to
openCL.  As this uses the GPU in a heavy way, I will implement multi-card
support on the host.
Is it a problem for you guys to think of tesseract 5.0 as a milestone?


2018-04-27 15:53 GMT+00:00 Janpieter Sollie <[email protected]>:

> if I'm right, a neural net is about the engine parts, not the image
> characterisation rendering method, am I right? because I see many
> presentations, and most of them talk about the history of tesseract, but
> that's not what I need
>
> 2018-04-27 14:27 GMT+00:00 ShreeDevi Kumar <[email protected]>:
>
>> Please see
>>
>> https://github.com/tesseract-ocr/tesseract/wiki/4.0-with-LSTM
>>
>> For info about neural nets used by tesseract
>>
>> On Fri 27 Apr, 2018, 7:48 PM Janpieter Sollie, <[email protected]>
>> wrote:
>>
>>> I had a quick thought about what you could offload to opencl.  I will
>>> need some help from you people (I am a C programmer, not C++, at least not
>>> experienced) to do the host code, but this algorithm is perfectly
>>> optimizeable in openCL.
>>> the way I'd do it:
>>>
>>> prerequirements:
>>> - you can define 65k offsets (x,y) in whose you want the openCL engine
>>> to look for dots (x,y), the optimal position and closest neighbour can be
>>> reported in the first part.
>>> - you can make a RAW image of both the image and the characters. size of
>>> the letters doesn't matter, but they must be trimmed properly
>>>
>>> 1. you give me a matrix of 256*256 offsets(short, short) to analyze,
>>> with a max of 64 dots (char, char) (I assume these are neurons) to analyze
>>> in each offset.
>>> so, this gives you a start memory usage of   2⁸ * 2⁸ *4 + 64*2 = 256k +
>>> 128 bytes
>>> each dot MUST contain a black pixel.
>>> then we add the image, this is a charimage of max (to be discussed with
>>> you guys), I assume a 4096*4096 pixel image would be fine, especially when
>>> a character can contain a 4x4 matrix defining a 0/1 (black/white) value.
>>> 2. Then I follow these steps in the openCL engine:
>>> - we analyze the neurons
>>>     - draw a cirle around them of x black points. (this circle can be 0,
>>> in which case the  neuron is white), for which the circle is completely
>>> black
>>>     - when we encounter one or more white points, a direction of the
>>> points is calculated. if there's no whitespace at the other side, the
>>> neuron offset is moved for x/2 in the opposite direction and analyze neuron
>>> is restarted for x/2.  else, quit the 'analyze neuron' part.  This can be
>>> done in local memory, in which case it will cost you 256*2=512 bytes of
>>> local ram to determine the optimal neuron position. Most graphic cards have
>>> a limit of 32k ram, so this is no problem :-)
>>> - determine the closest dot next to this one:
>>>     for each dot != this one, draw a line of black points, if no line
>>> can be found, jump to next dot.
>>>     watch distance.  If it's smaller than the previous neuron && this
>>> dot id hasn't a link pointing from the destination to this one, save dot id.
>>> so, at the end:
>>>     - each neuron of each offset is optimally centered in a return
>>> matrix of 256*256*64*2 = 2²³ = 8M of memory
>>>     - each neuron has a unique id to its closest neighbour, to which
>>> it's guaranteed to be attached. an id of -1 means no id could be found.
>>> 256*256*64 = 4M of memory
>>>
>>> 3. we focus on neuron list -> character mapping. this is a separate
>>> kernel. A "probability" factor is involved here, but I will think about it
>>> further.  I suggest to use a list of 64 character images at once, otherwise
>>> you need lots of memory :-)
>>> - define the top, left and right neuron. create a zoom factor for the
>>> image. calculate the aspect ratio.  The probability is
>>> 1-diff(aspect_ratio1, aspect_ratio2)
>>> - analyze each link in the font character. total probability *=
>>> (found_link_length / total_link_length)
>>> - report the probability.
>>> On the PC: the character with the highest probability is the character
>>> you 're looking for.  Be aware that you need to compare the possibilities
>>> of the different offsets if they overlap.
>>>
>>> if the tesseract project can use this, please let me know
>>>
>>> 2018-04-27 9:36 GMT+00:00 Zdenko Podobny <[email protected]>:
>>>
>>>> Only documentation we have is code itself ;-) But you can start with
>>>> searching for opencl issue in tesseract issue tracker on github...
>>>>
>>>> Zdenko
>>>>
>>>>
>>>> pi 27. 4. 2018 o 10:56 Janpieter Sollie <[email protected]>
>>>> napísal(a):
>>>>
>>>>> I'd be glad to help.  using tesseract 4, I am able to perform a 90%
>>>>> accuracy on OpenCL.  I do not have any experience with neural networks 
>>>>> (i'm
>>>>> just a high-school (no college educated IT-support guy with some knowledge
>>>>> about OpenCL), so can you recommend me some documentation to understand 
>>>>> the
>>>>> engine of tesseract 4?
>>>>>
>>>>> 2018-04-27 10:50 GMT+02:00 Zdenko Podobny <[email protected]>:
>>>>>
>>>>>> If you have experience your help will be warmly welcomed.
>>>>>> OpenCL is not maintained and it is on good way to be removed if
>>>>>> maintainer/contributor will not be found.
>>>>>> Anyway it is not used extensively, so there is a place for
>>>>>> improvement,
>>>>>>
>>>>>> Zdenko
>>>>>>
>>>>>>
>>>>>> pi 27. 4. 2018 o 10:21 Janpieter Sollie <[email protected]>
>>>>>> napísal(a):
>>>>>>
>>>>>>> Hello everyone,
>>>>>>>
>>>>>>> I have a question about the openCL selection procedure of tesseract:
>>>>>>>
>>>>>>> my output:
>>>>>>>
>>>>>>> [DS] Profile read from file (tesseract_opencl_profile_devices.dat).
>>>>>>> [DS] Device[1] 1:Fiji score is 0.202927
>>>>>>> [DS] Device[2] 1:Ellesmere score is 1.468799
>>>>>>> [DS] Device[3] 1:Ellesmere score is 1.468799
>>>>>>> [DS] Device[4] 1:Bonaire score is 1.533776
>>>>>>> [DS] Device[5] 1:Tonga score is 0.184236
>>>>>>> [DS] Device[6] 0:(null) score is 1.123015
>>>>>>> [DS] Selected Device[5]: "Tonga" (OpenCL)
>>>>>>>
>>>>>>> Ugh, this is weird .. why does tesseract take my Tonga instead of my
>>>>>>> fiji device?  can I force it to use the fiji?
>>>>>>> I understand the ellesmere have lower access times (they 're behind
>>>>>>> a pcie switch), but fiji and tonga are both directly connected via a 
>>>>>>> pcie
>>>>>>> 2.0 X16 bus.  Do we need a better tesseract selection procedure?
>>>>>>> If so, I'm quite skilled at opencl, I'd be glad to help!
>>>>>>>
>>>>>>> kind regards,
>>>>>>>
>>>>>>> Janpieter
>>>>>>>
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