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Many apps such as Tweetbot show thumbnails in their table view controllers for a much higher resolution image.
For example, this image shows a thumbnail that when tapped reveals the larger image:
I'm very confused how these images are loaded, however. My thinking would be that the original image is loaded and then shrunken down to the thumbnail size and displayed. However, I find this hard to believe as the image takes a decent amount of time to load/download at full resolution, so doing that for every single image just to shrink it would seem like it would take a decent amount of time. But these seem to load very quickly.
I'm also skeptical given that when you then tap the image it then takes a second to load before the full resolution image is shown, leading me to think that if they downloaded the full resolution before it would just be cached temporarily and loaded up instantly when the user taps it.
So I'm curious how exactly one would achieve a similar thumbnail system as in this app. Given a link to an image, such as the one shown in the image above, how would I very quickly take the image at the URL and present it as a thumbnail?
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A low-res version of the background quickly loads. Meanwhile, the higher resolution version is loading as a hidden image. When the high-res image is loaded, jQuery swaps the div's low-res image with the high-res version. This example would be efficient for changing one to many elements.
Low res images are loaded for each of the divs based on their CSS background-image settings. (Note that the CSS also sets the div to the intended dimensions.) Meanwhile, the higher resolution photos are being loaded as hidden images (all sharing a class name of img_highres).
Once you increase the resolution of an already lowered resolution image, it will not go back to its original form. This is because lowering the resolution loses some information about the image using the pyrDown method hence the results look a little blurred. This is different from scaling up an original image.
Open the image in Preview by launching Preview in the Applications folder. Alternatively, you can select Ctrl while clicking the image, and then choose Open > Preview . Under the Tools option on the menu bar, choose Adjust Size . In the Image Dimensions popup window, select if you want the adjustments to be done by Percent or Size .
Usually there are 2 images that are created by the server not the client, and the server provides 2 URLs for retrieving the images, one for thumbnail and one for the full res image ((this is what happens in 90% of the applications)), so your UIImageView (( or whoever is responsible )) is supposed to load the thumbnail, then load the full resolution image, and cache the latter, so that when you click on it it opens quickly. Now there are many cases:
If you want to achieve what you mentioned, this library can help you very much.
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