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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