I have a tableview that displays user uploaded PFImageViews. But the images load slowly because they are high res.
What is the most efficient (least costly) way to make images load quickly, while keeping the image size the same.
Current Approach:
Save the image twice (original file and low res file)
When displaying PFImageView, display the low res image
first, then asynchronously load the original image.
Is this the best approach?
Method 3:
For everything not in view of the user, do not load the images (delayed loader). That saves you the bandwidth and CPU to give the user the best possible experience.
Related
I have tried the following methods,
normal image upload.
encoding and decoding.
these two methods are taking long time to upload the image.
Any suggestion?
There are some simple ways:
Reduce the size of the image. From 1000x1000 to 500x500
Reduce the bpp of the image. For example instead of RGBA representation (32 bits per pixel) use RGB_565 (16bits per pixel) or even gray level image (8bits)
Reduce the quality of the image. Save it as .jpg. This will make the image much smaller. You can play with the quality parameter of jpeg. 100% means very high quality and large files, 1% means extremely tiny images (~40 times smaller) but all the details will be lost.
Save the image in Jpeg200 format. It reduces the size even further. Not every browser supports this format, so you might need to convert it to regular jpeg.
Use pyramids of images. For example. You have 1000x1000 image. Reduce its size by 2 to get 500x500, reduce again and again. Now you got 4 images 1000x1000, 500x500, 250x250, 125x125. You upload the 4 of them. Starting from the smallest to the largest. The smallest image will be uploaded very quick and you will be able to display it (though it is in lower resolution). Next when a better image arrives you update the display and resolution enhances. The effect would be that the basic image is loaded extremely fast and over time the resolution is enhanced. The transfer time of the 4 images will take only 30% more time than the original but the first one will arrive 64 times faster than the original
These are the basic solutions. If they are not what you needed please refine the question
I'm trying to optimize the loading time of my website.
Does requesting the same image in different places of the code increase load time?
For example, I'm using an image as background of a button and I'm loading the same image in different places of the website.
Is this a problem or since the file is the same in all the buttons the browser only loads it once?
If it's a problem, how can I optimize it? Thanks a lot!
no, repeating the same image multiple times should load it only once. You could even go further and actually use css sprites to have multiple images in one (one image which is a grid of images as a background within a smaller containing div and move it around with background position property)
The conditions:
It's a movie website with approximately 1000 images of 15kb
Approximately 70% of all images will be loaded on a page visit
Images will have a long expiry date.
I think I will chose CSS-sprites because most images will be loaded by the visitors any way. But the CSS-sprite of all images are 9MB and 15000x2000px. Even if I devide it into 3 sprites it's 3MB :S
Maybe such big sprites will cause some problems?
Will images be cached by the browser even if they are 3-9MB?
Will the big pixel dimensions be any problem for the browser?
Lazy load or CSS-sprite, what should I chose?
Please advice me!
Yes this will cause problems:
Due to the sprite size and dimensions, it will significantly consum cpu power
if you use it often on one page, it could even decrease scrolling and at least DOM manipulation actions
9MB is too big, do you have a link to that sprite ?
The browser will cache it, if the headers are set correct, that is not the problem
And you dont want to load a 9MB Sprite that is mandatory for a site !!! Mobile ?!?!!
Gekkstah
I'm building an image gallery type of application and i want to know what is the best image size and format (.png or .jpg) to be stored in the app.
I also want to know what is the best and most efficient way to store and load images natively.
PNGs are optimized for the OS when they are added to your app bundle. To improve performance of your app you want to:
Make sure the images have no alpha channel in them, otherwise the OS will try and blend them.
Resize your images to be the size they will end up in the UI. This will reduce the read bandwidth for the drawing, saving you memory and boosting performance.
Images in the app bundle can be read into UIImageViews:
UIImageView *newImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"myimage.png"]];
This will cache the image for you, which is good for lots of small images re-used a lot. For larger infrequently used images you want to use +imageFromContentsOfFile: instead of +imageNamed:
As far as I know iOS and xCode optimizes PNG formats and performs better with them.
You may want to check out this :
http://bjango.com/articles/pngcompression/
My app has more then 1000 photos and 50 galleries. It looks like as iphone Photos app. In preview list of gallery I have problem with performance.
In profile I saw what [sourceImage drawInRect:thumbnailRect] take 96% of time.
What is the best way to fix this issue?
Duplicate with small size of images I did.
Perhaps there is another solution?
Best way is to create thumbnail images for every Image File and save them as thumb_orginalimagefilename.png.
You can batch edit images in many desktop publishing programs.
Photoshop or Fireworks. In Picasa you can just multi-select a ton of images, like an entire folder and then Export to File and choose the output size
Create three large images that contain all of the thumbs in each gallery and load them in one UIScrollView with semi-transparent UIImageButtons over the locations where the thumbs appear in the image.
This could prove faster, since you only load one image per gallery, but you would have to try it to find out. I have done this before as it helped to reduce the size of my app.