@zdenko This discussion maybe better suited for tesseract-dev forum or do
you want to track it as a issue on github?

ShreeDevi
____________________________________________________________
भजन - कीर्तन - आरती @ http://bhajans.ramparivar.com

On Sat, Apr 28, 2018 at 1:19 PM, Janpieter Sollie <[email protected]
> wrote:

> 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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>>
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