Talk:Image scaling

Overly casual language
"This image shows the annoying effect that pixels of the original image are now squares" Not really very formal is it? 138.243.129.4 11:11, 30 December 2006 (UTC)


 * This is not currently an issue. yoyo (talk) 18:29, 5 April 2012 (UTC)

Image reduction
This article (and the linked articles) seem entirely focussed on Image enlargement. It would be good if reduction, and the effect of differing scaling routines on image quality were discussed. Particularly with regard to preservation of finer detail.
 * With multi-megapixel cameras ubiquitous these days, I find I'm scaling images down for web publishing and emailing a lot. —Preceding unsigned comment added by EasyTarget (talk • contribs) 09:19, 11 June 2008 (UTC)
 * Image reduction is important too! However, the old 'subsampling' page was hardly expansive.  Unfortunately I'm searching for the knowledge, not myself an expert, and not myself therefore in a position to improve this content.  Hopefully others will.  —Preceding unsigned comment added by 62.109.53.3 (talk) 10:27, 29 October 2008 (UTC)
 * It is worth noting that the "downsampling" link in this article links to an article relating to signal processing, not image scaling. The downsampling article itself contains a disambiguation link to the article "subsampling", which in itself turns out to be a disambiguation page, which, on the topic of image subsampling, points back to this article. --Dolda2000 (talk) 23:37, 12 February 2010 (UTC)

Proposal: merge from Subsampling
This other article about image scaling should be merged here. Dicklyon (talk) 17:35, 9 August 2008 (UTC)
 * I concur. A general cleanup on image scaling articles is needed, so I added a few more merge proposals. --Berland (talk) 19:45, 9 August 2008 (UTC)


 * If Resampling is included in the merge, it should be the main article title, since it's more general than image scaling. It might be best to leave a separate article on image scaling, as there's a ton of specific techniques for images, and leave the more general resampling separate. Dicklyon (talk) 19:53, 9 August 2008 (UTC)
 * It is only the bitmap part of Resampling I possibly want merged. But this is not my main field, so if both Resampling (bitmap) and Image scaling are separate enough for their own articles, it is fine by me. --Berland (talk) 21:19, 9 August 2008 (UTC)
 * Yes, you are right; most of that article should be merged; what's left may need to merge somewhere else. Dicklyon (talk) 04:18, 10 August 2008 (UTC)


 * Agree wholeheartedly that the image scaling articles should be re-arranged.
 * An important distinction is between continuous tone images and pixel art, as the goals and techniques are very different. Not sure which articles which information should go in though.
 * Nils von Barth (nbarth) (talk) 00:46, 14 September 2008 (UTC)

The article here (image scaling) only talks about digital images, while I guess that the title can refer to the analog domain as well. So from that image scaling may be the more general and maybe Resampling (bitmap) the more specific article and we should move the detailed descriptions of the digital algorithms and stuff over there - and add something about analog stuff here, of course.--Dvaer (talk) 19:28, 3 October 2010 (UTC)

Proposal: Merge From Bilinear interpolation section on applications to image processing
I believe that the Bilinear interpolation article section on "Applications to Image Processing" should not be merged to the Image scaling article because bilinear interpolation is used in many more image processing operations than just scaling. I, myself, am using it for re-sampling an image from Cartesian to polar coordinates. Others use it for re-sampling for perspective projection or inverse projection in image registration or texture mapping. I have also seen it used where one has a sparse grid of data points and one wishes to interpolate intermediate values -- for example, when one has a coarse grid of optical flow vectors in an image and wishes to interpolate the vector in-between to predict the motion of a pixel whose flow was not measured, one can use a bilinear interpolant for that velocity pair. This can happen in coarse-to fine algorithms like some versions of the Lucas-Kanade optical flow algorithm. Other coarse-to fine algorithms can require interpolation and use bilinear interpolants as well.

Because of this, bilinear interpolation's applications to image processing section cannot be properly merged into Image Scaling, or even image resampling.

A better proposal might be to have an article on applications of interpolation to image processing and list bilinear (along with bicubic, Gaussian, truncated sinc, etc., etc.) as different methods used, preferably with comments on the tradeoffs.

BrotherE (talk) 05:13, 7 March 2009 (UTC)


 * Thanks – these are very good points, and I’ll work them into relevant articles.
 * To summarize:
 * Resampling is not always scaling – it can also be a change of coordinate system (Cartesian to polar);
 * “Resampling” tends to imply “changing a uniform sampling rate”, but it can also be used in interpolation from sparse data, as you mention.
 * —Nils von Barth (nbarth) (talk) 12:48, 16 April 2009 (UTC)

Yep. This article is detailing a very different beast. I makes perfect sense to stay in its own page. &mdash; Kieff | Talk 11:53, 27 February 2011 (UTC)

Zoom...now enhance...
Do you think this article should say something about the "zoom and enhance" thing seen in CSI, etc.? Yes, I know it's impossible in real life, but lots of wiki articles have an "in popular culture" section. ' FL a  RN ' (talk)  21:50, 1 September 2010 (UTC)

Now that the article has been renamed
I noticed that this article has been moved from Pixel art scaling algorithms to Image scaling. The more general name needs to touch on algorithms intended for continuous tone images such as photographs and high-quality CGI, such as linear, cubic, and sinc resampling. --Damian Yerrick (talk | stalk) 13:28, 13 November 2011 (UTC)

And which is the best?
I want to use one of them in my project. Which is the best? As for me Hqx is the better choice. Your arguments? 178.49.101.206 (talk) 07:50, 10 January 2012 (UTC)Max

Depends on what your project is. Hqx is very processor intensive (compared to the others), so if you are working on something for a mobile device I would shy away from it. (Screen size would diminish the benefit, while limited processor and battery would amplify the downside). If neither of these are constraints, I would lean toward Hqx, so long as whatever you filtering isn't one of the several things Hqx does a poor job of scaling (You'll see it if you encounter it.) If you're not doing an emulator, I'd say you are better off hand-scaling your graphics though. — Preceding unsigned comment added by 98.118.85.79 (talk) 03:15, 7 February 2012 (UTC)

Example Video
The source image used has poorly rendered text, which makes it hard to tell whether or not the output is acceptable or not. Also, the excessive fades make it nearly impossible to tell the difference between each algorithm. Also, algorithm is spelled incorrectly. — Preceding unsigned comment added by 98.118.85.79 (talk) 03:12, 7 February 2012 (UTC)

Split tag
As stated at the top of this page, the section to be split off was in fact recently merged into this article. This would seem to be the correct place for it. The lede says that the article is about digital images, so it is not as if e.g. analogue scaling has been "unfairly" sidelined. The article may well need to be improved, but it does not need to be split. Op47 (talk) 15:28, 20 April 2012 (UTC)

Poor choice example image
The image containing the word "Wiki" already has antialiased edges, which makes it perhaps not as clear as possible where the antialiasing in the example output images comes from. The nearest-neighbour interpolated image, in particular, shows the antialiased edge, but it's really just showing the intermediate-valued pixels that are already in the original. Bernd Jendrissek (talk) 22:01, 10 September 2012 (UTC)

Super 2xSaI and Super Eagle
Which of the sentences extracted from the same paragraph is correct? -> Super Eagle [...] is similar to the 2×SaI engine, but does more blending -> Super 2×SaI [...] blends more than the Super Eagle engine — Preceding unsigned comment added by 201.68.160.227 (talk) 16:51, 22 February 2013 (UTC) It means that Super 2×SaI blends more than Super Eagle, which blends more than 2×SaI. Read correctly. 83.28.255.115 (talk) 19:17, 10 December 2015 (UTC)

Eagle

 * "Eagle works as follows: for every in pixel we will generate 4 out pixels. First, set all 4 to the colour of the in pixel we are currently scaling (as nearest-neighbor). Next look at the pixels up and to the left; if they are the same colour as each other, set the top left pixel to that colour. Continue doing the same for all four pixels, and then move to the next one."

This is different from the implementation, which checks 3 pixels instead of 2. I assume the pseudo-code is right and the text is incomplete. ? — Preceding unsigned comment added by 190.245.94.186 (talk) 21:56, 25 July 2013 (UTC)

Where's the 2xSaI pseudocode?
Thanks to the lack of information provided by the original uploader, of this article, I am presented with a wonderful pseudocode of the Eagle algorithm, but the 2xSaI algorithm remains left out. I need somebody to post it to Wiki here so I can implement it in a project I'm creating. I tried looking at the C source-code from its creator, but reading that code left my head spinning. Maybe somebody who's a wikipedian and who has significant knowledge of the workings of this specific algorithm can post it up here in this Wiki article for me as simple pseudo code for me so I can implement it in the software I'm writing. Benhut1 (talk) 09:50, 20 September 2014 (UTC)

Poor quality image
The HQ4x fish has very poor quality in the image that compares the original, HQ4x and 4xBRZ. It looks like the image that came from HQ4x has been saved in some lossy format like jpeg before it was enlarged and saved in PNG again. The image need to be updated, or removed, because as it is now it gives the impression that HQ4x is much worse than it really is. 90.227.25.67 (talk) 16:36, 17 January 2015 (UTC)
 * The poor quality has been fixed and the image has been moved to Pixel art scaling algorithms. Pjeo (talk) 16:45, 8 February 2017 (UTC)

External links modified
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De-bloating, and a start on re-writing
The image scaling article had become a bloated mess, mostly devoted to comparison galleries of images produced by a seemingly endless list of various fairly trivial algorithms. I've now de-merged the pixel art stuff into its own article, but too much of this article is still devoted to blow-by-blow comparisons of individual algorithms with inline images that takes up a lot of space to say very little. There is a good article to be written on image scaling, which is a subject with surprisingly deep ramifications into machine vision and the psychophysics of vision, but this isn't yet it. -- The Anome (talk) 10:23, 3 July 2016 (UTC)

Approaches for a reformulation of the article:


 * Describe early ad-hoc methods first
 * Simple approaches are basically attempts at resampling a two-dimensional band-limited signal
 * More complex approaches are basically attempts at the general function approximation problem, which is in turn generally approached (implicity or explicitly) as an inverse problem using knowledge from the universe of real-world images to provide appropriate priors
 * We really should mention the use of neural network approaches to the problem, see for example http://ejohn.org/blog/using-waifu2x-to-upscale-japanese-prints/
 * Pixel art re-scaling is a specialist topic that, while it fits within this overall framework, needs its own article to go into the many different ad-hoc algorithms that have been developed for this purpose
 * See also image reconstruction for the more general problem of which this is a sub-problem

-- The Anome (talk) 10:52, 3 July 2016 (UTC)
 * Nice, I have wanted to do that myselfCarewolf (talk) 12:47, 3 July 2016 (UTC)

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Super resolution vs Resolution enhancement technology
Hello,

Should the resolution enhancement in the third sentence of the introduction ″ In video technology, the magnification of digital material is known as upscaling or resolution enhancement.″ link to, as it currently does, https://en.wikipedia.org/wiki/Resolution_enhancement_technology or wouldn't https://en.wikipedia.org/wiki/Super-resolution_imaging be better?

37.136.2.21 (talk) 10:30, 16 September 2018 (UTC)

Removal of Real-Time Image Scaling Section
I suggest removing the real-time image scaling section that was added under applications. The listed temporal scaling APIs are not applications of any of the image scaling algorithms listed in this article and does not fit here. — Preceding unsigned comment added by 47.208.103.244 (talk) 22:10, 17 May 2022 (UTC)


 * Adding in that all video upscalers are real-time image scaling solutions. There are many real-time upscaling is not new, or limited to the graphics APIs listed.  The scalers in monitors/TVs are real-time upscalers and GPUs have been able to do real time image scaling outside these APIs for decades.
 * These are APIs to do upscaling of specific graphics elements in the rendering pipeline instead of post processing. 47.208.103.244 (talk) 16:45, 24 May 2022 (UTC)
 * Just pointing out that this content being removed from this article will not result in the other article being restored, if that's what you're trying to do in a roundabout way. Sergecross73   msg me  17:12, 24 May 2022 (UTC)