Bart_van_der_Wolf
pro member
Hi folks,
This post is a notification of the availability of a free tool for high quality image resampling (resizing). It is a works-in-progress project (hence the D.I.Y. title prefix), since the science behind it is also evolving, and there are a few inconveniences that yet need to be resolved.
The tool is a small Windows batch file, it can be downloaded here (link is updated to version 1.2.2). It depends on the availability of an already installed version of ImageMagick, an image processing toolkit that is usually operated from the command-line console. ImageMagick is also available for several other platforms, e.g. Mac OS and Unix/Linux, but the linked tool is specifically designed for Windows. However, it should be rather easy to translate it to another script dialect for other operating system script engines.
The Windows batch script file allows to drag an image onto the (icon of) the batch file in the file explorer or on the desktop. It can also be added to the Windows SendTo folder (e.g. 'C:\Users\YOURNAME\AppData\Roaming\Microsoft\Windows\SendTo' for Windows 7), which will then allow to right mouse-click on any image on your system and send it to the batchfile for processing.
The usage instructions are simple, just enter the required percentage (e.g. 50% will produce a copy at half the size of the original), or the maximum dimensions for an image (e.g. 800x800 will fit the longest dimension of your original image to 800 pixels, the smaller dimension will automatically scale proportionally, aspect ratio is maintained).
So what's so novel about it?
Well, image quality is usually negatively impacted by resizing (resampling) images. In addition to loss of sharpness, there are all sorts of artifacts that can be created, depending on image content and method of resizing. Aliasing artifacts of small repetitive features are very common on down-sampled images, e.g. for web publishing. Upsampling of images for larger print sizes may develop nasty halos around sharp edge transitions, and they will be easy to see because of the larger output size.
This is why there is ongoing research, as to which algorithms produce the best results. As a result of various on-line discussions (e.g. here, and here), a recent suggestion by a Canadian researcher (Nicolas Robidoux) has shown huge potential as a general approach that delivers high quality, low artifact, resized images. He asked me to try encoding his conceptual approach to facilitate further research into its optimization, which I did, and he has kindly allowed me to share the findings/scripted set of instructions that resulted.
Since the resized image quality is already so good, I decided to make a small batch script file for my own use, and share it with you for enjoyment.
There is still an issue that needs to be resolved though, and that has to do with the resulting file not having a color profile attached to it. So one is (untill I can find a simple solution) required to do that in a color-managed application that allows to assign the same profile as the original image had. Since many here use Photoshop, or similar applications that should only be an inconvenience, hopefully solved soon.
UPDATE, the colorprofile issue was fixed.
To be continued, image samples will follow.
Cheers,
Bart
P.S. The download link has be updated to point to the latest version (1.2.2)
This post is a notification of the availability of a free tool for high quality image resampling (resizing). It is a works-in-progress project (hence the D.I.Y. title prefix), since the science behind it is also evolving, and there are a few inconveniences that yet need to be resolved.
The tool is a small Windows batch file, it can be downloaded here (link is updated to version 1.2.2). It depends on the availability of an already installed version of ImageMagick, an image processing toolkit that is usually operated from the command-line console. ImageMagick is also available for several other platforms, e.g. Mac OS and Unix/Linux, but the linked tool is specifically designed for Windows. However, it should be rather easy to translate it to another script dialect for other operating system script engines.
The Windows batch script file allows to drag an image onto the (icon of) the batch file in the file explorer or on the desktop. It can also be added to the Windows SendTo folder (e.g. 'C:\Users\YOURNAME\AppData\Roaming\Microsoft\Windows\SendTo' for Windows 7), which will then allow to right mouse-click on any image on your system and send it to the batchfile for processing.
The usage instructions are simple, just enter the required percentage (e.g. 50% will produce a copy at half the size of the original), or the maximum dimensions for an image (e.g. 800x800 will fit the longest dimension of your original image to 800 pixels, the smaller dimension will automatically scale proportionally, aspect ratio is maintained).
So what's so novel about it?
Well, image quality is usually negatively impacted by resizing (resampling) images. In addition to loss of sharpness, there are all sorts of artifacts that can be created, depending on image content and method of resizing. Aliasing artifacts of small repetitive features are very common on down-sampled images, e.g. for web publishing. Upsampling of images for larger print sizes may develop nasty halos around sharp edge transitions, and they will be easy to see because of the larger output size.
This is why there is ongoing research, as to which algorithms produce the best results. As a result of various on-line discussions (e.g. here, and here), a recent suggestion by a Canadian researcher (Nicolas Robidoux) has shown huge potential as a general approach that delivers high quality, low artifact, resized images. He asked me to try encoding his conceptual approach to facilitate further research into its optimization, which I did, and he has kindly allowed me to share the findings/scripted set of instructions that resulted.
Since the resized image quality is already so good, I decided to make a small batch script file for my own use, and share it with you for enjoyment.
There is still an issue that needs to be resolved though, and that has to do with the resulting file not having a color profile attached to it. So one is (untill I can find a simple solution) required to do that in a color-managed application that allows to assign the same profile as the original image had. Since many here use Photoshop, or similar applications that should only be an inconvenience, hopefully solved soon.
UPDATE, the colorprofile issue was fixed.
To be continued, image samples will follow.
Cheers,
Bart
P.S. The download link has be updated to point to the latest version (1.2.2)
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