Talk:Bilinear interpolation

message: I think there is an error in the matrix formulation. Product of 2x2 and 1x2?
:Yes, you're right. Thanks for the notice. The error is now fixed. -- Jitse Niesen (talk) 05:53, 20 April 2006 (UTC)
thread_title: Error in matrix formulation

message: On using this page to check some interpolations we noticed that some minus signs should be plus signs. These have been changed. Otherwise this page is excellent. How about something similar in the tri-linear equations page?
:Are you sure? The formula used to be:
:: f(x,y) \approx \frac{f(Q_{11})}{(x_1-x_2)(y_1-y_2)} (x-x_2)(y-y_2) - \frac{f(Q_{21})}{(x_1-x_2)(y_1-y_2)} (x-x_1)(y-y_2) 
::::: {} - \frac{f(Q_{12})}{(x_1-x_2)(y_1-y_2)} (x-x_2)(y-y_1) + \frac{f(Q_{22})}{(x_1-x_2)(y_1-y_2)} (x-x_1)(y-y_1). 
:Substituing (x,y) = (x_1,y_2), the right-hand side evaluates to
:: - \frac{f(Q_{12})}{(x_1-x_2)(y_1-y_2)} (x_1-x_2)(y_2-y_1) = f(Q_{12}). 
:So the minus sign seems correct to me.
:It would be great if you could edit the trilinear interpolation page along similar lines. -- Jitse Niesen (talk) 04:09, 17 May 2006 (UTC)
replies: text: Of course, I could also be wrong. Please post the link, or email the code to me directly (you can find my email address by going to my user page and following the link to my home page). -- Jitse Niesen (talk) 03:43, 18 May 2006 (UTC)
thread_title: Error in Big equations

message: This article does not cite any references or sources. (difficult when I'm trying to find references for my coursework) Ms331 (talk) 22:35, 23 April 2008 (UTC)
thread_title: No citations

message: The palm tree image is very rough to start with.  Can someone do this with a better original image?daviddoria (talk) 20:23, 19 September 2008 (UTC)
thread_title: Bad Image for Example

message: The correct value should be 146.1, not 139.5  —Preceding unsigned comment added by Skogkatten (talk • contribs) 12:41, 18 November 2010 (UTC)
replies: text: I agree. Good catch. —Ben FrantzDale (talk) 13:11, 18 November 2010 (UTC)
thread_title:  Error in example picture: Bilinear interpolation in grayscale values. 

message: Could someone please explain what f(Q11), f(Q12), f(Q21), and f(Q22) actually are?
Everything else is explicitly defined, but I have no idea what the function for these points is calculating.  In other words, f(Q??) = ???
--61.194.119.130 (talk) 01:58, 30 May 2011 (UTC)
replies: text: Ok, I figured it out.  It is the value at the points Q11..Q22.--61.194.119.130 (talk) 02:00, 30 May 2011 (UTC)
thread_title:  I don't get it. 

message: Removed assertion that bicubic interpolation was superior to bilinear for various things including "edge halos" which is untrue. See The myth of infinite detail: Bilinear vs. Bicubic and closely compare the example images. Basically, bicubic is great if you like 135° angles and terrible if you don't like edge halos. Foogus (talk) 23:32, 27 October 2015 (UTC)
thread_title:  bilinear vs. bicubic 

message: Does the alternate algorithm (assuming the final functional form, and solving the matrix to find the weights) also trivially generalise to individual (convex) non-rectilinear quadrilaterals? (And what about convex quadrilateral meshes?) Cesiumfrog (talk) 23:39, 9 February 2017 (UTC)
thread_title:  Non-rectilinear quadrilaterals 

message: Notable omission in the article is what if any conventions exist for dealing with edge cases.  — Preceding unsigned comment added by Norlesh (talk • contribs) 07:26, 1 December 2019 (UTC)
replies: text: Which edge cases? Sampling at the edges of the image? I'd say that there's no convention for this because of the ad hoc nature of this problem. BernardoSulzbach (talk) 18:18, 6 December 2019 (UTC)
thread_title:  treatment of edge cases 

message: I found the formula with b_xx coefficients would be very useful, but I couldn’t figure out how is the derivation done with only the final formula provided. It might be a lot better to add more information and explanation of that formula. :-) 1.36.219.240 (talk) 20:04, 7 May 2020 (UTC)
thread_title:  Explanations or Derivation of the second Alternative formula 

message: The matrix formula for unit square interpolation has x and y transposed.
Shg4421 (talk) 20:08, 19 July 2021 (UTC)
thread_title:  Formula error