This is in regards to the pictures taken through the iPhone's camera. No matter what, I can't understand why image sizes are in the order of 1000s and image scale always 1.0.
For example, I printed out an image's details and this is what I got:
<UIImage: 0x134def110> size {3024, 4032} orientation 3 scale 1.000000
What does 3024x4032 mean? And why is the scale 1.0, when my screen size is really 375x667? Orientation 3 means the image is roated 90º counterclockwise. So if the original image is 375x500 (in pixels), after rotation it should be 500x375. Then why does the size shown not change accordingly?
And on a similar note, how would I get the size of the image in pixels from this size that's printed out? Because no matter what the size of the camera preview, if the ratio of the camera preview is 4:3, the resulting size of the image (image.size.width and image.size.height) is always 3024x4032.
What does 3024x4032 mean?
Those are the dimensions of the image. I think you're missing one point: the iPhone's camera can take photographs with a much higher resolution than its screen size. Just because an image is shown on the screen, it doesn't mean the image dimensions are that size.
Size: An uncropped, landscape 12.2MP photo (that's default size when shot on the iPhone 7 rear camera) is 3024 * 4032 pixels, so that's where that number comes from. Extra crispy in case you want to frame it and hang it up on your wall! See source.
Scale: Generally 1.0 (or 100%), it's the magnitude of which you've reduced your image file size. So if you wanted a 50% smaller file, you could scale the image down to 0.5 (50%), obviously losing some quality in the process.
tl;dr: those dimensions are the scale of the photo in storage, not the dimensions at which it's rendered on the phone.
Related
I have one ImageView but the width and height are not constant. Both will change as per device width and height. (Height of ImageView is 1/3 of screen size and width is complete device width)
Example:
Proper Colors
Height
Width
iPhone SE
375
222.5
iPhone 11 Pro Max
414
298.67
iPhone 12 Pro Max
428
308.67
iPhone 12
390
281.33
As we see, width and height are varying so in this scenario what should be size for 1x image. Once we get 1x size then 2x and 3x sizes we can find easily.
Note: If width and height is fixed then I know how to find 1x, 2x and 3x.
Example: If imageView is 20x20 then, 1x = 20x20, 2x = 40x40, 3x = 60x60, But in above scenario width and height is not constant.
Note: If width and height is fixed then I know how to find 1x, 2x and 3x. Example: If imageView is 20x20 then, 1x = 20x20,2x = 40x40,3x = 60x60
#1x, #2x, #3x has more to do with the pixel density of the screen and not the size of the image. If the same sized image is displayed on a higher resolution screen then iOS will automatically choose a #3x version of the asset. Think of video quality on YouTube, a 720p and 1080p has the same size. But the 1080p video is more clear.
But in above scenario width and height is not constant.
As to dealing with the changing size of the screen, you need to decide before hand how your images should be displayed. This is a UI designing concern. UIImageView has various ContentMode options that you can use. For example,
scaleAspectFit: The option to scale the content to fit the size of the view by maintaining the aspect ratio. Any remaining area of the view’s bounds is transparent.
So if you use scaleAspectFit then on larger screen sizes you will have more blank space to the sides of the image.
Also, please take a look at Apple's Human Interface Guidelines for Image Size and Resolution and 1x, 2x and 3x Image Scaling on iOS Explained blog post.
The coordinate system iOS uses to place content onscreen is based on measurements in points, which map to pixels in the display. A standard-resolution display has a 1:1 pixel density (or #1x), where one pixel is equal to one point. High-resolution displays have a higher pixel density, offering a scale factor of 2.0 or 3.0 (referred to as #2x and #3x). As a result, high-resolution displays demand images with more pixels.
When you can fit more pixels on the same screen real-estate, you also need higher resolution images. This is where 1x, 2x and 3x come in. You provide higher resolution image files for the same assets, which are automatically selected by iOS when your app runs on a high-PPI iPhone model.
I have a UIView that works as camera and it's 320x180 and a UIImageView of same size.
When I take a photo, it generates me an UIImage of size 1080x1920, so when I show it on the imageView, what happens is that the photo is very compressed on its height, because it is very tall, is like this
██████ the black rectangle is the whole photo (1080x1920)
██████
█▒▒▒▒█ the gray is what camera show in screen
██████ (it shows only gray part but it stores
██████ all the black part 1080x1920)
I would like to store it as an UIImage exactly how I see it on the gray rectangle.
I'm not sure how to do this, since the size of the photo is way bigger than the resolution the screen (which is 320 x 568) so is hard to crop correctly (and the crop is also rotating the image and bringing other bugs).
1080/6 = 180. 1920/6 = 320. So the values are in the correct aspect ratio — but they are reversed. You need to apply the correct rotation value to the image.
If I create an image view that has constraints that are proportional to the size of the screen. I can't decide the exact dimensions of image I need to supply for any of x1, x2 or x3. I understand how image sets work. But it's figuring out the dimensions I need because when I the following code I get slightly different dimensions for every device I test on:
print(imageView.bounds.size.width)
print(imageView.bounds.size.height)
Different x2 devices like the iPhone 5 and iPhone 6 will give me slight differences. But because they receive the same image, will it not look different?
Add an Aspect Ratio constraint on your UIImageView to make sure you don't stretch the image.
Use Aspect Fill or Aspect Fit content mode for UIImageView.
Keep the biggest image for each scale factor (2x, 3x). Basically, there are multiple device resolutions for 2x scale factor, so #2x image should have resolution designed for iPhone 6 and it will be automatically downscaled on smaller devices (iPhone 5/4s). 3x image should have resolution for
I need to implement some photo uploading function, but I'm a little bit confused because of the pixel/size dimension of the images. I need to display a square cropped image which size in IB is 320 x 320.
I've made a little research, but couldn't find an exact answer. I've checked Instagram, and it uses 640 x 640 pixel images everywhere. How is that possible? The iPhone 6 Plus's screen resolution is bigger then the Full Hd, the width of the screen is 1136 px while an Instagram image is 640 px wide (and doesn't pixelated) . I don't think that they save images for every devices separately.
So UIImageView can display non-retina images on retina screens like this? Or what's the reason why the 640 px is enough?
UIImageView can scale the image you pass to it. So if you were to pass a 640x640 pixel image into a UIImageView that was displayed larger on screen, it would be scaled to fit appropriately. It would scale up and you would lose quality when displayed that way.
As for the IB size being 320x320 points, that doesn't directly translate to pixels. Older devices worked that way, but newer (retina) devices scaled at 2x (including the iPhone 6). So a 320x320 pt UIImageView in IB would actually render at 640x640 pixels. The 6 Plus renders at 3x, so 960x960 pixels.
I'm not sure how you concluded that Instagram was using 640x640 on all devices, but if that is the case, the 6 Plus is scaling images to 960x960 pixels and losing quality. It's possible that the loss isn't noticeable in most cases, but I would guess they request larger images for the larger screen.
http://www.paintcodeapp.com/news/ultimate-guide-to-iphone-resolutions
The photo taken using the UIImagePickerController is of 4:3 aspect ratio. However, the full screen aspect ratio is 3:2. So the gallery app is doing some magic to show the photo as 3:2 aspect ratio. When you zoom out in the full screen view, the photo appears in 4:3 aspect ratio. Can anyone shed light on how it could be done? I've been breaking my head for the past two weeks on this.
Really appreciate the help!!
To fit a 4:3 image into a 3:2 space you can either match the height or match the width.
If you were to match the height then you'd turn the 3 in 4:3 into the 2 in 3:2. So you'd scale the entire image by 2/3. Since you'd be scaling width and height by the same amount, the effective height after scaling would be the 4 from 4:3 scaled by 2/3, to give 8/3 — a bit less than three. You'd therefore not quite fill the screen.
Conversely, if you were to match the width then you'd turn the 4 in 4:3 into the 3 in 3:2. So you'd scale the entire image by 3/4. Since you'd be scaling width and height by the same amount, the effective height at the end would be the 3 from 4:3 scaled by 3/4, to give 9/4 — a bit more than two. You'll therefore slightly more than fill the screen.
So that the photos app does is display pictures with an initial zoom so as to fit the width of the stored image to the width of the display. If the stored image is 3264x2448 (which I think it is on the iPhone 4S and the 5) then on an iPhone 4s — using points rather than pixels — it's scaled by a ratio of 480/3264. If you work that out, it gives the image a final height of very close to 360pt, 40pt wider than the screen.
In terms of UIKit, that probably means putting a UIImage inside a UIScrollView and setting the initial value of zoomScale to 480/3264 (ie, approximately 0.15). The scroll view can help you with zooming in and out though there's still some manual work to be done — see e.g. this tutorial. By setting a minimumZoomScale of 320/2448 (ie, approximately 0.13) you'll automatically get the behaviour where zooming out as far as you can go ends up showing the entire 4:3 image on screen.
not sure how you obtain your image, but you might have gotten one of the representations of the image. One of those representations is specifically for getting a quick fullScreen CGImage, an other will return the FullResolution. FullScreen will be whatever is needed for the device (640x960 on iPhone4), Full resolution would be the 8MP picture.