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According to my understanding if pixels per inch are increased on the screen, the content should only look better.

Now when I use my Mac I see a lot of programs which have blurry text when viewed on a Retina display. Why does every app need to be updated to work with retina display on mac?

Edit: I wanted to add something more interesting, if you install Windows on a mac pro retina with all the latest drivers it would look absolutely gorgeous. The Win7 drivers support retina display really well and I don't have to install applications on Win7 that support retina display specially.

So I feel that it is something which which is only done by OSx because everything works fine in Windows really.

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Please migrate this question to – Tushar Mathur Mar 12 '13 at 19:17
What resolution do you use for the Retina screen? – Daniel Beck Mar 12 '13 at 20:03
This question wouldn't be a good fit for Photography. Please read their FAQ – this question isn't specific to photography at all. – slhck Mar 12 '13 at 20:20
@daniel, its scaled to hd. – Tushar Mathur Mar 12 '13 at 20:25
There's your problem. Use the actual native retina solution (with fewer effective pixels) and you should be good. The same reasons not to use non-native resolutions on TFT screens apply here as well. – Daniel Beck Mar 12 '13 at 20:34

If PPI is increased, the app should look smaller. If it has to appear the same size as before then it needs to be suitably scaled. Now with vector graphics this is not a problem since these are resolution independent, but most apps employ a lot of bitmap/raster graphics resources which are resolution dependent. Scaling the latter can lead to varying amounts of blurriness depending on the image's properties, the amount to be scaled, the scaling algorithm employed and so on.

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I don't quite agree with you. Increasing te size of the image in terms of inches should distort images, not ppi. – Tushar Mathur Mar 12 '13 at 7:33
I couldn't understand your sentence above at all: "Increasing te size of the image in terms of inches should distort images, not ppi." Say the image was 100px square and was displayed on a screen 1" square. Now PPI increased from 100 to 200, so the same image is 0.5" square. If you scale it up 2x so it again covers a 1" square area, it will be blurred to some extent depending on the scaling algo used. I am not a graphics expert so I freely admit I might be wrong, but what I wrote above does seem correct to me. Do you have a better explanation so I can improve my understanding too? – Karan Mar 12 '13 at 18:02
Sorry for not being clear, distortion depends on the ratio of image size (in pixels) and the distance between the image and the eyes. By that I mean if you have a picture which is of HD quality and one which is of HD+ quality if you dont move your head the HD+ should look better. If you move you head towards the picture the image will appear more and more distorted. A good example would be the extremely large LCD display which are in the malls. They look quite clear when you are away from them but the more near you get to them the worse they look. – Tushar Mathur Mar 12 '13 at 18:49
"picture quality depends on the size of a pixel as perceived by the eyes" - Yes, so when the PPI doubles, the pixels have become half the size they were before. So a 100px image (going by my example above) will now take up only 0.5" physical area where earlier it covered 1". The image should look smaller and sharper now if it is not scaled. But if the OS scales the same image to fit the higher pixel density screen, you have each image pixel being duplicated so the image can cover 200px instead of 100. Naturally in this case blurriness will result, right? – Karan Mar 12 '13 at 19:02
Yes, it's still taking up 1" of space after scaling, but the pixel size has changed! To make it fit the same physical 1" space, each pixel of the image has to be doubled, which according to me will result in some amount of blurriness. If you simply double PPI without scaling the image, the image will not take up 1", it will only look to be 0.5" in size. – Karan Mar 12 '13 at 19:07

FULL DISCLOSURE: I don't know, here is what I think.

if you just up the resolution you get more screen real estate. However, if the display size stays the same everything gets a lot smaller. So, Apple put a display with a very large number of pixels and then turned down the dots per inch in the operating system to make everything take up more space, so in the end things seem the same size

Why does this make some apps look bad? I'm guessing they override GUI drawing api's and the OS scales the resolution for these apps instead of the DPI which makes them look stretched.

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If you use the "Best (Retina)" setting so that everything is pixel-doubled:

Images and icons look about the same because of integral scaling. But text in non-Retina apps looks clearly worse. The difference is that on a non-Retina display, text uses sub-pixel rendering. But with Retina, old apps use full-pixel anti-aliasing instead. (Those full pixels are then multiplied perfectly with integral scaling.)

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Are you saying that Retina displays dont have antialiasing ? – Tushar Mathur May 10 '13 at 9:47
No -- presumably Retina apps on a Retina display use sub-pixel rendering or anti-aliasing. Not that you can necessarily tell, since the pixels are so tiny anyway. The issue is that when text normally uses sub-pixel rendering, which is sharper than full-pixel anti-aliasing, you can't simply pixel-double that SPR as you can a full pixel of color. It's easier to describe with a white board and RGB colored pens.... – Ken May 10 '13 at 20:36
Please ken if you could explain it a little more it would be helpful for others also. – Tushar Mathur May 11 '13 at 9:21

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