I’m new in iOS and trying to make simple app with hierarchy of viewcontrollers. In the last one I wanna display scrollable image (which can also be zoomed at least x1,5), containing some small black and white picture and a piece of text. Initially I planned to make vector image, convert it to .jpg and use UIScrollView for displaying. But I found out that .jpg ( approx. 150 KB) didn’t provide a good quality for displaying text. As I have to use a lot of images I don’t want to increase image size. What is worse I also want it look good on retina display.
Can you recommend a way how to display image, containing text, with enough quality?
I mean that I don’t want the user see the separate pixels of letters in the text. Just like when you read text in your e-mail in iOS. Image size should be as small as possible. Planning physical size of image – approx. 5 cm x 15 cm.
Any help much appreciated
Thanks
To get good edges you would need to use png not jpg, which will make the image sizes much larger. I have a better suggestion, more code but better solution.
The answer is to not put the text into the image, but to draw it over it in real time.
You would:
associate text at some coordinate in the image (say a CGRect) with the image
create a uiimageview subclass that in the drawRect routine, after calling super, draws the text using the NSString categories on UIKit (which let you draw into a context)
To get going on this please create a small one vc project and get the subclass working there, then back port it to your primary project.
Related
Out of sheer interest:
Is there any difference, specifically in (theoretic) performance or memory usage between using a UIImage of 25x25 pixels, square, one color, png on the one hand, or a UIView of the same size and color?
Consider the Unread bullet in Mail.app. Would you use an image for that? Or a UIView with rounded edges?
An image takes more space, and resided in a UIImageview, and has a resolution dependency, but on the other hand, once it is loaded, it wouldn't make too much difference, would it?
If you use UIImageView then it requires image. Where if you use UIView you not need image, so it makes your application light weight. Second thing, large image takes more memory to load. So, it is always beneficial to use UIView instead of image wherever possible! It keeps your application light weight and can give better performance!
An UIImageView, being a subclass of UIView, will instantiate a regular view with all the extension that UIKit developers have built to support displaying an image inside a plain UIView. By doing that you're only creating an extended (aka possibly heavier) version of a standard UIView.
That said, using an UIView for simple UI elements (like Mail.app's bullet icon) will also allow you to forget about the resolution of the graphical asset since you don't have to care about #2x or #3x resolutions resulting also in a smaller project size.
Of course you'll only save kilobytes when it comes to simple shapes, but reusing this pattern all across the app will benefit you exponentially in the long term.
I am displaying a grid of images (3rows x 3 columns) in collection view. Each image is a square and its width is determined to be 1/3 of collectionView's width. Collection view is pinned to left and right margin of the mainView.
I do not know what the image height and width will be at runtime, because of different screen sizes of various iPhones. For example each image will be 100x100 display pixels on 5S, but 130x130 on 6+. I was advised to supply images that exactly matches the size on screen. Bigger images often tend to become pixelate and too sharp when downsized. How does one tackle such problem?
The usual solution is to supply three versions, for single-, double-, and triple-resolution screens, and downsize in real time by redrawing with drawInRect into a graphics context when the image is first needed.
I do not know what the image height and width will be at runtime, because of different screen sizes of various iPhones. For example each image will be 100x100 display pixels on 5S, but 130x130 on 6+
Okay, so your first sentence is a lie. The second sentence proves that you do know what the size is to be on the different screen sizes. Clearly, if I tell you the name of a device, you can tell me what you think the image size should be. So, if you don't want to downscale a larger image at runtime because you don't like the resulting quality, simply supply actual images at the correct size and resolution for every device, and use the correct image on the actual device type you find yourself running on.
If your images are photos or raster type images created using a raster drawing tool, then somewhere you will have to scale the original to the sizes you want. You can either do this while running in iOS, or create sets up front using a tool which can give you better scaling results. Unfortunately, the only perfect image will be the original with everything else being a distortion of the truth.
For icons, the only accurate rendering solution is to use vector graphics. Tools like Adobe Illustrator will let you create images which you can scale to different sizes without losing clarity. Unfortunately this still leaves you generating images up front. You can script this generation using most tools and given you said your images were all square, then the total number needed is not huge. At most you need 3 for iPhone (4/5 are same width, 6 and 6+) and 2 for iPad (#1 for mini/ipad1 and #2 for retina).
Although iOS has no direct support I know of for vector image rendering, there are some 3rd party tools. http://www.paintcodeapp.com/ is an example which seems to let you import vector images or draw vector images and then generate image code to run in your app. This kind of tool would give you what you want as the images are now vector drawings drawn at the scale you choose at run time. $99 though.
There is also the SVGKit (https://github.com/SVGKit/SVGKit), but not sure how good/bad this is. It seems to let you simply load and render direct from SVG files. Might be worth trying.
So in summary, I think you either generate the relatively small subset up front using a tool you can control the output from, take the hit in iOS and let it scale the images or use a 3rd party vector to image rendering kit which would give you what you want.
I have a series of images that I would look to loop through using iOS's [UIView startAnimating]. My trouble is that, when I exported the images, they all came standard in a 240x160 size, although only 50x50 contains the actual image, the rest being transparent parts that are just taking up space.
When I set the frame of the image automatically using image.size.width and image.size.height, iOS takes into images' original size of 240x160, so I am unable to get a frame that conforms to the actual parts of the image. I was wondering if there is a way using Illustrator or Photoshop, or any other graphics editing software for me to export the images based on their natural dimensions, and not a fixed dimension. Thanks!
I am a fan of vector graphics and thinks everything in the world should be vector ;-) so here is what you do in illustrator: file - document setup - edit artboards. Then click on the image, and the artboard should adjust to the exact size. You can of course have multiple artboards, or simply operate with one artboard and however-many images.
I'm using Tesseract OCR 3.01 in my iOS application, it shows 90% accuracy for my data when I pick an image from my phone’s library. But if I use the same image from the camera, it is showing jumbled letters. I followed this tutorial, kindly guide me if something can be done to make sure it works from camera as it works for gallery images.
Yup, There are three things to be specific, First of all, OCR works well with black and white images rather than colored, So If you could try to convert your image to B&W, it would increase accuracy.
The second thing is the size and orientation, You need to force the image to be of 640*480 or 320 size, this would increase both the speed of recognition and the accuracy as well, For orientation , there are a lot of ways to manage.
Finally, If some how you can allow the user to specify Exactly where or on which part of the image he wants to perform the OCR, this greatly increases the accuracy and time since the library does not need to check the entire image for text, rather you already specify the part to be searched for.
PS:I have been working on creating an OCR app for the past few weeks.
Almost for sure the problem is "orientation". Apple tends to create images in one bit map form - the image bits are laid out as if the camera was on its side with the volume buttons top and right. Images that you see which appear taller than wider are still laid out as above, but there is an "orientation" in the EXIF object included with the image.
I'm going to guess that tesseract does not look at the EXIF, but expects the image in a "standard" format so that text is in the position it would be for a person reading the text.
You can test my hypothesis by using camera images taken with volume button top right.
If they work, then what you will need to do is process the image yourself, and re-arrange the bits per the orientation setting. This is not all that hard to do but will require you to read up on vImage and/or bit map contexts.
I displays a splash Screen when my app loads,There is a background image in the splash screen,I problem is how can I make fit this image in all types of blackberry models?
Keep in mind that many BlackBerry devices have different screen resolutions and even different aspect ratios. So if you just use a single image and resize (stretch and/or squish) it to fit the current screen, you're going to distort the image (or pattern). As I see it, there are two main approaches:
1) Use a different image for each screen resolution. There are about 7 different resolutions that cover most of the in-market devices (240x260, 240x320, 320x240, 360x400, 360x480, 480x320, 480x360)
2) If it's a regular background pattern as opposed to a picture or logo, just have one image in the app that's big enough to cover the largest screen size (480x360) and for all other screen sizes just clip it. In fact, I think this should happen automatically if you just set the background image - anything that can't be displayed on the screen will be clipped.
While approach #2 is better in terms of reducing application size, I'm going to guess that since you're asking this question the background you're thinking of using isn't a regular pattern.
I think the simplest method would be to use the setBorder method of whatever screen/field needs a stretched background. For example:
Border b = BorderFactory.createBitmapBorder (new XYEdges (), bitmap);
field.setBorder(b);
In my experience this results in the background image being stretched and provides the simplest method for fitting the size you need. I have only ever used it for fields though and never a MainScreen so it might not work for you.