Difference between CGAffineTransform on CIIMage and UIImageView
I have been playing around with CGAffineTransform and noticed that transforming an image from the UIImageView has a different effect then transforming it directly through the CIImage. Here is the code:
let totalTransformationAndRotation = CGAffineTransform(rotationAngle: x)
// How I transform using the imageview
self.keyImage.transform = totalTransformationAndRotation
// How I transform using the image
var coreImage:CIImage? = myImage!.ciImage
if coreImage == nil {
coreImage = CIImage(cgImage: myImage!.cgImage!)
}
coreImage = coreImage?.transformed(by: totalTransformationAndRotation)
When used separately these two transformations come out totally differently. I understand that the unit is different for the CIImage's transformation's dx and dy and UIImageView's transformation's dx and dy, but even rotations have a different result. It appears to me that when rotated in the CIImage. The rotation is centered around the bottom left, while in the UIImageView it is centered around the center of the image.
Is it possible to rotate, scale and translate a UIImage/CIImage and have the same effect as if you applied the same transformations on a UIImageView?
Edit:
I am trying to transform a UIImage by rotating, scaling, and translating. I have gotten the desired effect by applying a transforming on the UIImageView's transform property but realized that I need to do the transformation directly in the image.
swift uiimageview core-image cgaffinetransform ciimage
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
|
show 4 more comments
I have been playing around with CGAffineTransform and noticed that transforming an image from the UIImageView has a different effect then transforming it directly through the CIImage. Here is the code:
let totalTransformationAndRotation = CGAffineTransform(rotationAngle: x)
// How I transform using the imageview
self.keyImage.transform = totalTransformationAndRotation
// How I transform using the image
var coreImage:CIImage? = myImage!.ciImage
if coreImage == nil {
coreImage = CIImage(cgImage: myImage!.cgImage!)
}
coreImage = coreImage?.transformed(by: totalTransformationAndRotation)
When used separately these two transformations come out totally differently. I understand that the unit is different for the CIImage's transformation's dx and dy and UIImageView's transformation's dx and dy, but even rotations have a different result. It appears to me that when rotated in the CIImage. The rotation is centered around the bottom left, while in the UIImageView it is centered around the center of the image.
Is it possible to rotate, scale and translate a UIImage/CIImage and have the same effect as if you applied the same transformations on a UIImageView?
Edit:
I am trying to transform a UIImage by rotating, scaling, and translating. I have gotten the desired effect by applying a transforming on the UIImageView's transform property but realized that I need to do the transformation directly in the image.
swift uiimageview core-image cgaffinetransform ciimage
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
There is no such thing as a UIImage transform. Your example involves CIImage, a very different thing. If you want help doing an image transformation please state clearly what the exact goal is. If you are just trying to draw the image rotated, I wouldn’t do it any of the ways you’ve shown so far.
– matt
Nov 25 '18 at 19:21
Thanks, @matt I fixed it.
– joshLor
Nov 25 '18 at 19:36
Ok but the CIImage is still not how I would do it. I would just redraw the image into an image graphics context with a transformed CTM. Again, I could demonstrate if you would be specific.
– matt
Nov 25 '18 at 19:43
Or see my discussion at apeth.com/iOSBook/ch15.html#_graphics_context_transforms
– matt
Nov 25 '18 at 19:49
@matt which one is faster? I may have to do hundreds of the transformations concurrently
– joshLor
Nov 25 '18 at 20:05
|
show 4 more comments
I have been playing around with CGAffineTransform and noticed that transforming an image from the UIImageView has a different effect then transforming it directly through the CIImage. Here is the code:
let totalTransformationAndRotation = CGAffineTransform(rotationAngle: x)
// How I transform using the imageview
self.keyImage.transform = totalTransformationAndRotation
// How I transform using the image
var coreImage:CIImage? = myImage!.ciImage
if coreImage == nil {
coreImage = CIImage(cgImage: myImage!.cgImage!)
}
coreImage = coreImage?.transformed(by: totalTransformationAndRotation)
When used separately these two transformations come out totally differently. I understand that the unit is different for the CIImage's transformation's dx and dy and UIImageView's transformation's dx and dy, but even rotations have a different result. It appears to me that when rotated in the CIImage. The rotation is centered around the bottom left, while in the UIImageView it is centered around the center of the image.
Is it possible to rotate, scale and translate a UIImage/CIImage and have the same effect as if you applied the same transformations on a UIImageView?
Edit:
I am trying to transform a UIImage by rotating, scaling, and translating. I have gotten the desired effect by applying a transforming on the UIImageView's transform property but realized that I need to do the transformation directly in the image.
swift uiimageview core-image cgaffinetransform ciimage
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
I have been playing around with CGAffineTransform and noticed that transforming an image from the UIImageView has a different effect then transforming it directly through the CIImage. Here is the code:
let totalTransformationAndRotation = CGAffineTransform(rotationAngle: x)
// How I transform using the imageview
self.keyImage.transform = totalTransformationAndRotation
// How I transform using the image
var coreImage:CIImage? = myImage!.ciImage
if coreImage == nil {
coreImage = CIImage(cgImage: myImage!.cgImage!)
}
coreImage = coreImage?.transformed(by: totalTransformationAndRotation)
When used separately these two transformations come out totally differently. I understand that the unit is different for the CIImage's transformation's dx and dy and UIImageView's transformation's dx and dy, but even rotations have a different result. It appears to me that when rotated in the CIImage. The rotation is centered around the bottom left, while in the UIImageView it is centered around the center of the image.
Is it possible to rotate, scale and translate a UIImage/CIImage and have the same effect as if you applied the same transformations on a UIImageView?
Edit:
I am trying to transform a UIImage by rotating, scaling, and translating. I have gotten the desired effect by applying a transforming on the UIImageView's transform property but realized that I need to do the transformation directly in the image.
swift uiimageview core-image cgaffinetransform ciimage
swift uiimageview core-image cgaffinetransform ciimage
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
edited Nov 25 '18 at 20:14
joshLor
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
asked Nov 25 '18 at 19:17
joshLorjoshLor
485416
485416
There is no such thing as a UIImage transform. Your example involves CIImage, a very different thing. If you want help doing an image transformation please state clearly what the exact goal is. If you are just trying to draw the image rotated, I wouldn’t do it any of the ways you’ve shown so far.
– matt
Nov 25 '18 at 19:21
Thanks, @matt I fixed it.
– joshLor
Nov 25 '18 at 19:36
Ok but the CIImage is still not how I would do it. I would just redraw the image into an image graphics context with a transformed CTM. Again, I could demonstrate if you would be specific.
– matt
Nov 25 '18 at 19:43
Or see my discussion at apeth.com/iOSBook/ch15.html#_graphics_context_transforms
– matt
Nov 25 '18 at 19:49
@matt which one is faster? I may have to do hundreds of the transformations concurrently
– joshLor
Nov 25 '18 at 20:05
|
show 4 more comments
There is no such thing as a UIImage transform. Your example involves CIImage, a very different thing. If you want help doing an image transformation please state clearly what the exact goal is. If you are just trying to draw the image rotated, I wouldn’t do it any of the ways you’ve shown so far.
– matt
Nov 25 '18 at 19:21
Thanks, @matt I fixed it.
– joshLor
Nov 25 '18 at 19:36
Ok but the CIImage is still not how I would do it. I would just redraw the image into an image graphics context with a transformed CTM. Again, I could demonstrate if you would be specific.
– matt
Nov 25 '18 at 19:43
Or see my discussion at apeth.com/iOSBook/ch15.html#_graphics_context_transforms
– matt
Nov 25 '18 at 19:49
@matt which one is faster? I may have to do hundreds of the transformations concurrently
– joshLor
Nov 25 '18 at 20:05
There is no such thing as a UIImage transform. Your example involves CIImage, a very different thing. If you want help doing an image transformation please state clearly what the exact goal is. If you are just trying to draw the image rotated, I wouldn’t do it any of the ways you’ve shown so far.
– matt
Nov 25 '18 at 19:21
There is no such thing as a UIImage transform. Your example involves CIImage, a very different thing. If you want help doing an image transformation please state clearly what the exact goal is. If you are just trying to draw the image rotated, I wouldn’t do it any of the ways you’ve shown so far.
– matt
Nov 25 '18 at 19:21
Thanks, @matt I fixed it.
– joshLor
Nov 25 '18 at 19:36
Thanks, @matt I fixed it.
– joshLor
Nov 25 '18 at 19:36
Ok but the CIImage is still not how I would do it. I would just redraw the image into an image graphics context with a transformed CTM. Again, I could demonstrate if you would be specific.
– matt
Nov 25 '18 at 19:43
Ok but the CIImage is still not how I would do it. I would just redraw the image into an image graphics context with a transformed CTM. Again, I could demonstrate if you would be specific.
– matt
Nov 25 '18 at 19:43
Or see my discussion at apeth.com/iOSBook/ch15.html#_graphics_context_transforms
– matt
Nov 25 '18 at 19:49
Or see my discussion at apeth.com/iOSBook/ch15.html#_graphics_context_transforms
– matt
Nov 25 '18 at 19:49
@matt which one is faster? I may have to do hundreds of the transformations concurrently
– joshLor
Nov 25 '18 at 20:05
@matt which one is faster? I may have to do hundreds of the transformations concurrently
– joshLor
Nov 25 '18 at 20:05
|
show 4 more comments
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There is no such thing as a UIImage transform. Your example involves CIImage, a very different thing. If you want help doing an image transformation please state clearly what the exact goal is. If you are just trying to draw the image rotated, I wouldn’t do it any of the ways you’ve shown so far.
– matt
Nov 25 '18 at 19:21
Thanks, @matt I fixed it.
– joshLor
Nov 25 '18 at 19:36
Ok but the CIImage is still not how I would do it. I would just redraw the image into an image graphics context with a transformed CTM. Again, I could demonstrate if you would be specific.
– matt
Nov 25 '18 at 19:43
Or see my discussion at apeth.com/iOSBook/ch15.html#_graphics_context_transforms
– matt
Nov 25 '18 at 19:49
@matt which one is faster? I may have to do hundreds of the transformations concurrently
– joshLor
Nov 25 '18 at 20:05