My app requires that each user has a profile picture of around 140*140px. Right now I am using jpgs, I am wondering if performance wise it will be better to use pngs. I read pngs are good for small UI elements and images, jpg for large images with detail such as photos. Obviously my profile pics are photos but they are small. Would it make much difference switching to png? Thanks
JPEG is best for small file sizes of photos, even for low resolutions.
PNG makes sense when there are many pixels of the exact same color next to each other. This is not the case with photos.
These should be helpful for you.
When to use PNG or JPG in iPhone development?
PNG vs. GIF vs. JPEG vs. SVG - When best to use?
Apple optimizes PNG images that are included in your iPhone app bundle. In fact, the iPhone uses a special encoding in which the color bytes are optimized for the hardware. XCode handles this special encoding for you when you build your project. So, you do see additional benefits to using PNG's on an iPhone other than their size consideration. For this reason it is definitely recommended to use PNG's for any images that appear as part of the interface (in a table view, labels, etc).
As for displaying a full screen image such as a photograph you may still reap benefits with PNG's since they are non-lossy and the visual quality should be better than a JPG not to mention resource usage with decoding the image. You may need to decrease the quality of your JPG's in order to see a real benefit in file size but then you are displaying non-optimal images.
File size is certainly a factor but there are other considerations at play as well when choosing an image format.
Related
I am into iOS development from past 1+ months and what I have experienced is that I have to put images for 1x 2x 3x for iphone and then 2x retina for ipad. One of the experienced designers has sugguested to me to go for svg format as it scales itself according to the screen sizes.
So my elaborated questions are:
Can I use svg instead of png?
Is it necessary to still put images in 2x and 3x for iphone and ipad if I'm using svg?
Will the images in svg scale according to the phone size and not lose quality?
If any other information according to your experience please share.
Thank you.
Official iOS Dev documentation says "the PNG format is the one most recommended for use in your apps". You can read it for a lot more information here.
Yes, although the supported file types table doesn't list it. Apple values user experience. SVG scaling consumes a few more CPU cycles which they don't like. PNG rendering is more efficient than SVG.
Yes, Apple explicitly recommends using multiple versions of the image at different sizes. Then scaling can be done from the file having the nearest dimensions.
Refer 1. There are cases like zoom-in / out scenarios where SVGs would be better though.
You could use vectorized PDFs alternatively. You can read more here. It isn't without limitations, but with vectorized PDFs, Xcode automatically generates scaled versions. That should make life easier. Note that sometimes the scaled results look quite poor.
I have been looking at SVGKit and I am finding conflicting ideas. Some say it's slower than PNG and others saying it is fast.
I was hoping to get a recommendation and which route I should take. When I am exporting my vector graphics to PNG for display, would it not make sense to use an SVG instead ?
Of course this gives the added value that it remains a vector.
Or is it still recommended in exporting everything to a PNG ?
You might consider the middle-way introduced in Xcode 7. Here you add your assets to the project as vector images (PDF) and at build-time Xcode automatically generates the PNGs in all needed sizes (1x, 2x, 3x).
Personally, I only use SVGs when necessary, like if I need to be able to change the color of the (parts of the) image. I believe there can be a performance hit when resizing vector images at run-time, although Android uses vectors as default, so it might be insignificant.
SVG is most resource intensive and can be used if you need to display something that can be zoomed in and out while PNG should be preferred for most UI graphics (logos, icons, etc.), as it is crisp yet remains lightweight and fast to display so there is no way to compare SVG with PNG in term of Performance.
if you are going after a Crystal clear images you can use pdf based graphics, which are supported by Xcode Using Vector Images in Xcode
if you still need to implement SVGKit i always suggest using some tools (like SVGCleaner) to clean and simplify SVG in order to enhance performance.
I am developing my first app (iOS universal app), I want to reduce my app's size because it contains many images (png files) and sounds(mp3 files).
So my problem is:
How can I reduce the size of my app (images and sounds)?
Thanks!
Images:
Only include the basics in your app bundle (i.e. app icons, launch image, and possibly images for the first page)
Use Parse (or any other similar service) to download any additional images after the app is downloaded.
This approach will significantly decrease the size of your app but also let you pull down additional image files as needed.
Sounds:
What is the type of sounds files you're using? .caf files are incredibly large. Using .aifc files are just as good quality (to my untrained ear at least) and takes up significantly less space
Depends, compress png images to jpeg usually reduce app size, there are also image optimizers that compress pngs. If your images are part of the UI, tile them or stretch them really helps you in reduce app size and also memory usage. The image asset function in Xcode 5 helps in you in create resizable images.
For sounds the concept are pretty close to images, use compressed file audio as eckyzero said.
If your sounds and images aren't part of the UI but resources, you can make the app download them from the internet at first launch.
I have an app that have a LOT of images (some are in jpeg, others in PNG).
This image must be in bundle because the app need to run offline.
I tried to zip the images but does not make much diference.
I was thinking in compressing the images, but since they have different types will be a lot of work do decode then beside they can't lost quality.
My app has 300mb.
Any ideas ?
EDIT
Those images are from are downloaded by a script, my app have an embed sqlite (make by a script too) mapping then.
Most of then are pictures with 600x600 approach.
JPEG and PNG images are already compressed. Trying to compress them further won't help significantly; it'll just make your application more complicated, and make it take longer to display the images.
Converting PNG images to JPEG, where appropriate, or compressing JPEG images at a lower quality setting, may save you a considerable amount of space.
I have a simple question for anyone who knows the answer to this... I am making a social photo sharing app and I want to save a large enough image in the app so that it can be used in a full screen website app moving forward. Think...Facebook.
I've been playing around with JPEG compression in iOS and also testing sizes and quality with Photoshop CS5. I get really different results with these two. In photoshop, even at high compression, the image is quite clear and retains lots of detail. In iOS, once the compression dips below about 0.5 it looks horrible and blocky. It almost seems like there's a point where the image quality just dips after a certain magic compression number.
With photoshop, I use the "Save for Web" option and with iOS I am using UIImageJPEGRepresentation(image, 0.6). Is there a huge difference in these two? Aren't all JPEGs use the same kind of compression?
I am really not that informed in this world of image processing. Can anyone advice me on what is a good way to have images compressed to a level that preserves quality and stay bandwidth friendly? I want my images to stay about 1280px in length.
Any advice on this or smarter ways to move JPEGS over the network is welcomed. Thank you.
If your app is producing images from an iOS device, you should continue to use UIImageJPEGRepresentation. I don't think it's productive comparing the UIKit JPEG compression to Photoshop's.
I would find a JPEG compression level you're happy with using the available UIKit APIs and go with that. When you're serving up 30+million images a second it might be worth looking at optimisations but until then leave it to UIKit.