Talk:Pixel density

message: What is HiDPI? Wikipedia redirects the search of HiDPI to this page, but it appears nowhere in this article.   — Preceding unsigned comment added by 67.163.157.221 (talk) 03:51, 12 November 2013 (UTC)
replies: text: It's defined in Named pixel densities 71.178.175.63 (talk) 17:15, 4 November 2020 (UTC)
thread_title: HiDPI

message: The article said:
   "For example, a display that is 11 inches wide by 8.5 inches high, capable of a maximum 1024 by 768 pixel resolution, can display about 93 PPI in both the horizontal and vertical directions."
...changed it to 788, as 768/8.5 gives 90.3, not 93...  —Preceding unsigned comment added by 132.207.137.202 (talk) 15:57, 12 June 2008 (UTC)
thread_title: Definition

message: 1. Mention typical confusion with DPI -- even used commonly in manufacturer descriptions. In the DPI article, disambiguate: DPI refers to printing but often used incorrectly for monitors - for monitors see PPI.
:-- Seems to be mentioned now, but rather confusingly. It says "...commonplace to refer to PPI as DPI, which is incorrect because PPI always refers to input resolution". The very first sentence of the article, however, starts a list with "displays" (not for touch input), and the very next sentence after the quoted one mentions photographs ("quality photographs usually require 300 pixels per inch"), so this whole "input/output" idea does not quite seem to be well-established. At least some source would need to be added to see where this idea (or the confusion ;) ) comes from. (Luna Kid (talk) 09:25, 1 December 2013 (UTC)
thread_title:  Article Issues 

message: I came across the following, is it correct?
A 26" monitor with a resolution of 1920x1200 have a PPI of 87.
sqrt(1920^2+1200^2)/26 = 87  —Preceding unsigned comment added by Frap (talk • contribs) 10:15, 22 February 2008 (UTC)
thread_title:  Calculation 

message: This article claims that the popular and mistaken myth of bigger pixels equaling better image quality (less noise). The dpreview-articele(s) on this issue is/are not factual, but also only repeating the myth.
In reality the tiny sensors of pocket cameras with their tightly packed pixels have better signal/noise ratio than the DSLR-cameras with the large photosites, surprising, but true. The real reason why DSLR-cameras produce better images is the fact that their sensors have roughly 10 times the light sensitive surface area.
The reason why this myth exist is the peoples habit of stydying noise by examining images that are magnified so that each pixel on the computer screen equals one pixel in the image. This is however problematic way of studying noise as for example if we have two sensors of equal size, sensor A having 5 Mp, sensor B having 10 Mp, on a 100% view it sure seems as if the 10 Mp sensor produces inferior signal/noise ratio, but in reality we are not comparing sensors A and sensors B, but sensor A versus a 5 Mp crop of sensor B (ie. comparing 100% of sensor A area with 50% of sendor B area).
--88.195.100.60 (talk) 12:01, 4 March 2009 (UTC)
thread_title:  Pixel density and noise in digital cameras 

message: " For instance, a 100x100-pixel image that is printed in a 1-inch square could be said to have  100 the printer's DPI capability."
Okay, for someone like me (layperson), this makes absolutely no sense. – Kerαunoςcopia◁galaxies 14:07, 27 February 2010 (UTC)
thread_title:  English please 

message: I'm struggling with understanding PPI with digital photography, and this article basically has zero information on it. Are images taken with a DSLR always 300 ppi? How come a vertical image is sometimes labeled as 72 ppi (at least for me; I use a Nikon D80)? What's the relationship between PPI and image size, if any? What's the relationship with PPI and printing quality, if any? The section I jumped to talked about photodiodes and something about cm2. This means nothing to me and isn't in any sort of context that I can understand. Also, run-on sentences, poor punctuation, so I tagged the article "copyedit." Please expand, cheers! – Kerαunoςcopia◁galaxies 14:14, 27 February 2010 (UTC)
thread_title:  Disappointing article 

message: The article claims that the iPhone 4 has "arguably the highest display pixel density actually available to the general public in a mass market device to date," but in reality, many modern digital cameras have the same or higher pixel density in their LCD displays. I only know this because I decided to do the math on the supposed ppi on my own camera, a Panasonic Lumix DMC-ZS3, which has a 3" (4:3) display that boasts 460,000 pixels. Doing the math, I came to the conclusion that it has 326 ppi, the same as the iPhone 4, and the Panasonic ZS3 has been commercially available since 2009, while its previous model, the Panasonic Lumix DMC-TZ5 had the same LCD specs, and was released in 2008.
The main problem with trying to calculate the ppi in digital camera displays is that they don't typically tell you what the resolution is, but the final approximate pixel count, so you have to work your way back from there, but if that's not enough to convince you that there has already been "mass market devices" with "higher display pixel density" than the iPhone 4, consider the Sony Cyber-shot DSC-G1, released in 2007, it has a 3.5" display (the same size as the iPhone 4), with a display count of 921,000 pixels. In comparison, the iPhone 4's display is 960x640, or 614,400 pixels, or more than 300,000 pixels less in the same display area. -Glenn W (talk) 05:37, 23 July 2010 (UTC)
thread_title:  Apple's iPhone 4 (highest display pixel density claim) 

message: I'm wondering given the accuracy an encyclopedia is supposed to have, how the image on the front can claim to be 200 pixels by 200 pixels - for use of measuring on a display and calculating PPI - If I copy that and display it on my Amstrad CPC, it will be a rectangle unless I am in Mode 1, because mode 2 the pixels are twice as tall as they are wide, and mode 0 they are twice as wide as they are tall.  Assumptions that pixels are square are bad as it is not the case. talk 17:14, 17 March 2012 (UTC)
replies: text: so a square is a square because the coordinates not because the appearance? Meaning if its 2x2 and x isn't the same size as y its a square? I was led to believe the length of x and y had to equal to be a square obviously with the same unit of distance in standard units for both x and y. If each x is twice as large as each y then you obviously have a rectangle. ZhuLien 66.249.80.203 (talk) 09:01, 8 March 2014 (UTC)
replies: text: I know what you mean and don't want to argue about that. For the square example in the page however, if the "square" doesn't appear as a square of your screen it gives the added information that its pixels are non-square and then you can measure horizontal and vertical PPI independently. That is just a feature. Not that in that case you have two numbers. See my writings in other sections of the talk page. comp.arch (talk) 09:11, 21 March 2014 (UTC)
thread_title:  Image of the square 

message: This graphic is meaningless as it changes scale when you scale the total webpage up and down while scrolling the mouse wheel and holding down ctrl.  — Preceding unsigned comment added by Ironbrooo (talk • contribs) 01:42, 20 March 2012 (UTC)
thread_title:  200 x 200 pixel image 

message: As PenTile technology has already captured a significant portion of mobile display manufacture, is DPI now a much more useful attribute than it was when relevant portions of this article were written?
If anybody knows how to derive true pixel density- or traditional RGB stripe subpixel equivalent from PenTile manufacturers' claimed PPI, a new section would be a good place for that information. Patronanejo (talk) 08:50, 21 July 2012 (UTC)
thread_title:  PenTile Displays 

message: The article mentions the term "quality factor" without definition.  "This delivers a quality factor of 2, which delivers optimum quality. The lowest acceptable quality factor is considered to be 1.5 ... "  The only "quality factor" I can find on web searches are a scientific oscillatory systems. What is an "optimium" quality factor? The acceptable quality "is considered" by whom? Bwagstaff (talk) 18:21, 26 August 2013 (UTC)
replies: text: I also find this strange. Why isn't there a wiki page on "quality factor", and why should quality factor be mentioned in the intro to the page and nowhere else? Dylan Thurston (talk) 22:04, 22 January 2015 (UTC)
thread_title:  Another big missing definition, "Quality Factor" 

message: Note: All modern displays as far as I know use square pixel and have for a long time. My first thinking and input here that I since deleted was wrong so this is mostly academic. So no need to read further? Old CRTs at least, could be configured for different resolutions even non-square (do not have an inherant density).
Example: 1000 x 1000 pixels. 10 inces wide and high. Diagonal is calculated with Pythagoras, 14.14 inches. Horizontal PPI (and vertical) 1000/10 = 100 PPI. The length in pixel along a diagonal in pixels can't be any longer than 1000 (see manhattan distance). Then diagonal PPI is really 1000/14,14 = 70 PPI (article would still 1414/14.14 = 100 PPI). Both are kind of right.
Same display 1000 x 1000 squished to be 5 inces wide (double horizontal density but same vertical): diagonal length is now 11.18 inches. Article would calculate 1000/11.18 = 89.4 PPI.
If you however had cut the first screen in half 1000 x 500. Now it's "widescreen", horizontal and vertical density are still the same, 100 PPI. Suddenly actual calculated diagnonal density is: 1000/11.18 = 89.44 PPI (article would say 1118/11.18 = 100 PPI). comp.arch (talk) 15:21, 5 November 2013 (UTC)
thread_title:  FYI: PPI calculation only works for square pixels and gives only horizontal or vertical PPI 

message: "usually written in lowercase ppi"  might not be a good WP:RELIABLE source? The Wikipedia article is not consitently using one or the other - should it? Similar to DPI, I've always written in upper case myself (it is an acronym, byt so is ppcm.. that treally chould be lower case - the cm part at least.. PPcm? :) ) comp.arch (talk) 02:49, 11 January 2014 (UTC)
thread_title:  PPI vs. ppi 

message: Sources talking pixel destiny always use ppi, never ppcm. 
Please don't let this be another case of "kibytes", where Wikipedia took a proud stand for confusion and disarray by using units noone else uses. Regards, CapnZapp (talk) 15:28, 12 January 2014 (UTC)
thread_title:  Use pixels per inch, not ppcm 

message: Apple is now one of many companies selling phones and computers with screens with high pixel density. (Several editors predicted this in Retina Display's deletion discussion five years ago.) The article notes that in practice Apple has simply doubled or tripled the pixel density of its displays instead of following the 300 ppi declaration that Jobs made in 2010. Such displays are now commonplace, and we don't have any similar articles for other phone or display vendors' marketing terms. Hence, I would like to propose merging the content of two articles. Jc86035 (talk) 15:05, 5 October 2017 (UTC)
thread_title:  Proposed merge with [[Retina Display]] 

message: It's been there since May 2014, and nobody's ever paid any attention to it.
I believe it should be speedily removed: What's WRONG with a guidebook, anyway?
I thought the purpose of an article is to be useful, regardless of style.
--AVM (talk) 21:45, 9 January 2018 (UTC)
thread_title:  HEY, when is someone going to remove that pesky "manual" template? 

message: The first sentence of this article says this:
"Industry standard, good quality photographs usually require 300 pixels per inch, at 100% size"
This makes no sense.  A number expressed as a percent indicates a fraction of something.  But fraction of what?  100% of what?  You can't resize a piece of paper, which is what the paragraph is talking about, so it must be talking about the size of the original image as it looked on the computer screen.  But if you have an image on the computer screen that's 1 inch square, and you shrink it by 50%, a 1 inch region of your computer screen still contains the same number of pixels, it's just showing an altered image that essentially has every other pixel removed.  Likewise, if you there's a 1 inch region of your computer screen, and it has a certain pixel density because of the resolution you are driving your monitor at, and you take an image and expand/resize it using an algorithm that interpolates colors between pixels, it's still the same number of pixels on the screen at the DPI of your monitor.  So the amount that the source image has been enlarged, or shrunk, is totally irrelevant.  The only relevant factor is whether that 1 inch square section of the paper, at 300 DPI, has enough fine detail for you to resolve details that you would have been able to resolve on a monitor at a given resolution.  Or taking an analog photograph for example as the gold standard, assuming a photograph that's 1 inch square, you can resolve a certain level of detail, and we are asserting that 300 DPI can allow us to see that same level of detail.  But if you put that same analog photo negative through an enlarger, you'll see more detail, because the photo negative actually includes finer detail than you can actually see.  Or you could use the enlarger to shrink it.  Either way, at the end, you get a new print, and there's a certain level of detail that you can visually ascertain.  We are saying here that 300 DPI allows us to resolve that same level of detail.  The zoom level of the photo just determines WHAT TYPE of details are actually being seen.  It's a completely independent variable and it's irrelevant.  — Preceding unsigned comment added by 2620:0:1003:1214:3595:2520:E774:2068 (talk) 23:06, 29 March 2018 (UTC)
thread_title:  100% size?