title: How to handle image scale on all the available iPhone resolutions?
body: <p>What sizes would be the best to use for images: background.png, background@2x.png and background@3x.png if we want to use this image for example to cover the full width and half height of the screen on all resolutions for iPhone portrait app?</p>
  <p>This is what we have now:</p>
  <pre><code>Device                        Points   Log. Res.  Sc. Real Res.  PPI  Ratio   Size
  iPhone 12 Pro Max, 13 Pro Max 926x428  2778x1284  3x  2778x1284  458  19.5:9  6.7&quot;
  iPhone 12, 12 Pro, 13, 13 Pro 844x390  2532x1170  3x  2532x1170  460  19.5:9  6.1&quot;
  iPhone 12 mini, 13 mini       812x375  2436x1125  3x  2340x1080  476  19.5:9  5.4&quot;
  iPhone XS Max, 11 Pro Max     896x414  2688x1242  3x  2688x1242  458  19.5:9  6.5&quot;
  iPhone XR, 11                 896x414  1792x828   2x  1792x828   326  19.5:9  6.1&quot;
  iPhone X, XS, 11 Pro          812x375  2436x1125  3x  2436x1125  458  19.5:9  5.8&quot;
  iPhone 6+, 6S+, 7+, 8+        736x414  2208x1242  3x  1920x1080  401  16:9    5.5&quot;
  iPhone 6, 6S, 7, 8, SE2       667x375  1334x750   2x  1334x750   326  16:9    4.7&quot;
  iPhone 5, 5S, 5C, SE1         568x320  1136x640   2x  1136x640   326  16:9    4.0&quot;
  iPhone 4, 4S                  480x320  960x640    2x  960x640    326  3:2     3.5&quot;
  iPhone 3GS                    480x320  480x320    1x  480x320    163  3:2     3.5&quot;
  </code></pre>
  <p><img src="https://i.stack.imgur.com/0jwdF.png" alt="iPhone resolutions" /></p>
  <p>Some people say that for edge to edge image (like a banner on the bottom from left to right edge of the screen) for iPhone 6 Plus they would prepare back@3x.png with width 1242 and for iPhone 6 back@2x.png with width 750 to match the iPhone 6 screen size however I do not think that this is a good idea because 1242 / 3 = 414 and 750 / 2 = 375 so naming them as @2x and @3x does not have sense. And then what width should have back.png - 375 or 414?</p>
  <p>Graphics names are using @2x and @3x suffixes so if for example image@3x.png has 30x30 resolution then logically thinking image@2x.png should have 20x20 resolution and image.png should be 10x10. This means that if we want to have sharp full width image for each screen then we probably should create back@3x.png with width 414<em>3=1242px, back@2x.png with width 414</em>2=828px and back.png with width 414px. This however means that on every iPhone except for iPhone 6 Plus you will need to setup your uiimages to use for example aspect fit content mode and they will be scalled down so this again is not a perferct solution and probably would really slow down the application if we use a lot of scalling on older devices.</p>
  <p>So what do you think would be the best solution to solve this problem?</p>