ConvImgs

Software for RISC OS by Chris Johnson


Process options

If you are a user of DPScan (by David Pilling) the process options available here will be familiar to you. If you are not sure how or when some of these options would be useful, and you have DPScan, then use it with some test images to see the possibilities.

Rotate/flip
If this option is ticked, each image will be transformed by rotation or flipping before type conversion and saving. The current setting for transform type is shown to the right, and may be changed by clicking on the popup menu button and selecting a new setting from the menu that appears.

The options available are

  • rotate left 90°
  • rotate 180°
  • rotate right 90°
  • flip horizontal
  • flip vertical

Note that there is no 'Auto-rotate' option - only some types of file can store orientation information, and even with those files, it is optional. If you wish to 'auto-rotate' jpeg images from e.g. a digital camera, then use my other application !TransJPEG (available from my web site) to do this.

Resize
If this option is ticked, each image will be transformed by resizing before type conversion and saving. The current setting for resizing method is shown to the right, and may be changed by clicking on the popup menu button. A dialogue box will be opened.

There are currently four options for resizing.

Resize by
This will rescale the image by the percentage shown in the field to the right.
Resize X to
This will scale the images to the width (in pixels) entered in the field to the right. The aspect ratio of the image will be preserved.
Resize Y to
This will scale the images to the height (in pixels) entered in the field to the right. The aspect ratio of the image will be preserved.
Fit within
This will resize the images such that they fit within the height and width values specified. If the button Ignore aspect is not ticked then the aspect ratio will be preserved. If it is ticked then the image will be stretched in one of the directions to completely fill the specified size.

If the option 'Allow scale up' is ticked, then the images will be scaled up if necessary to fit the size, otherwise images smaller than the set dimensions will be left as is. This setting applies only to the last three options. If the 'Resize by' value is greater than 100%, then this will always be honoured.

The SET button should be clicked to apply the new settings.

Histogram
If this option is ticked, the range of pixel intensities in the image will be expanded to cover the full range from black to white.

The current setting for histogram expanding is shown to the right, and may be changed by clicking on the popup menu button. A dialogue box will be opened.

This allows the setting of

  • the number of intensity levels used in the calculation, currently 32 to 256, the maximum
  • the intensity threshold (as a percentage of the maximum intensity in the image) used when searching the histogram for levels to discard at each end

The SET button should be clicked to apply the new settings.

A fuller description of this option may be found here.

Filter
If this option is ticked, each image will have a filter applied before type conversion and saving. The filter that will be applied is shown to the right, and may be changed by clicking on the popup menu button. The current options are:

Various levels of sharpening or blurring are available. The option 'Slight sharpen' is probably the one to use to reduce the softness of digital camera images.

Convert to greyscale
This will convert the image to a greyscale image. There are no additional settings for this option.
Invert image colours
This option will invert all the colours in the image, and is probably of most use for black and white line art images. Some users have found it useful when scanning diagrams as TIFF files, which then come out as 'negative' in some software.

There are no additional settings for this option.


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ConvImgs is © Chris Johnson, 2013
Email:chris@chris-johnson.org.uk