Talk:Otsu's method

message: I really do not understand why there are two javascript implementations that are nearly identical. The only significant difference is that the second variant also provides code to load and convert an rgba image to grayscale and then apply otsu's method. The link to an offsite result page is weird, too. I suggest to remove the second variant.  — Preceding unsigned comment added by 2A02:8071:308A:2100:7AE4:FF:FE4E:8683 (talk) 13:18, 18 May 2016 (UTC)
thread_title: Javascript Variants

message: this page needs a visual example of a grayscale image thresholded using Otsu's Albert Cruz 23:15, 1 July 2008 (UTC)
replies: text: I've linked a public domain image (original) and it's otsu's threshold result. they could probably be better formatted Albert Cruz 03:32, 3 July 2008 (UTC)
thread_title: Visual example

message: I'v changed from :Category:Computer vision to :Category:Computer vision stubs since this articles needs mora material to make it readable.--KYN 07:01, 22 March 2006 (UTC)
replies: text: I changed the description so that it is clear that variances are not computed. --Tomash (talk) 22:10, 16 February 2008 (UTC)
thread_title: General/Content

message: the references at this point have been well formatted; however there is some information missing on sources 2 and 3 (Ping-Sung Liao and Tse-Sheng Chen and Pau-Choo Chung (2001) and  N. Otsu (1979)). the volume and issue numbers need to be checked. Albert Cruz 03:32, 3 July 2008 (UTC)
thread_title: References

message: The article states (misleadingly) that the threshold applies to the dynamic range of pixel intensities present in the image. This comment (and the reference provided for it) refers to the internal MATLAB function graythresh that implements Otsu's algorithm in this way. In fact the description of the algorithm given here, as well as all the pseudo-codes seem to be providing a real threshold value, and do not seem to be using the dynamic range. This is what it appears to me, but I have done neither experimentation, nor verification. If someone else does that, they could fix the article. If not, I will do so when I have to time to verify my claim. Arif Zaman (talk) 12:37, 29 October 2015 (UTC)
thread_title: Dynamic Range

message: This pseudo code has nothing to do with Otsu's Method.
This method's describes the iterative method to obtain the ideal threshold by Gonzalez and Woods [2002].
Pseudo code is an example of K-mean method... not Otsu's
:Pseudo-code now reflects what I think is Otsu's algorithm. --Tomash (talk) 22:10, 16 February 2008 (UTC)
thread_title: Psuedo-code

message: The article states the method represents "histogram shape-based image thresholding".  
However it sounds more like a clustering-based method.
—DIV (138.194.12.32 (talk) 08:40, 10 August 2010 (UTC)
thread_title:  Category 

message: In ,  changed the number  .7152 to  .07152, apparently believing the number .7152 to have been the result of vandalism by an IP (see WP:HD#Need help reverting vandal.  He gives no evidence for the diagnosis of vandalism, and the IP's value of .7152 seems to be supported by a range of published sources, such as http://research.ijcaonline.org/volume49/number9/pxc3880757.pdf, https://rdrr.io/bioc/EBImage/man/channel.html, http://www.bioconductor.org/packages/release/bioc/manuals/EBImage/man/EBImage.pdf, and http://cmm.ensmp.fr/~marcoteg/cv/publi_pdf/amira/2016_IET_AdaptiveBinarisationSceneText.pdf (to name but a few).  I have therefore reverted Penubag's change, pending any further evidence. --David Biddulph (talk) 03:10, 8 May 2017 (UTC)
replies: text: Run the code in your browser like it suggests. The correct output is only obtained by .07152, as was originally written in the first revision. See here  -- penubag  (talk) 03:19, 8 May 2017 (UTC)
replies: text:  That sounds rather like WP:OR, but other users can judge that against the published sources.  Do you have an example with the value .7152?  With further WP:OR it can be noted that in the variant gray = red * .2126 + green * .7152 + blue * .072, the 3 coefficients add up to 1, which may have been the intention;  experts in the field can perhaps confirm if necessary? --David Biddulph (talk) 03:29, 8 May 2017 (UTC)
replies: text: Here is the image with .7152 which is incorrect. For now, I'll revert the IP's unsourced change because clearly it makes the example incorrect.  -- penubag  (talk) 03:34, 8 May 2017 (UTC)

text:  Those who understand such things may also wish to look at Grayscale (with the .7152 value). --David Biddulph (talk) 03:55, 8 May 2017 (UTC)
replies: text:  .7152 also occurs in Luma (video). --David Biddulph (talk) 03:58, 8 May 2017 (UTC)

text: Suggest that the most correct thing to do -- regardless of the correct green value -- would be to remove large amounts of OR (ie: code  implementation) from the page.  ~Hydronium~Hydroxide~(Talk)~ 10:17, 8 May 2017 (UTC)
thread_title:  Reversion of unsourced change