Legacy ImageMagick Discussions Archive

If you have a large number of these to process, using Gimp or similar to get white samples would be tedious and error-prone. A fairly simple script with IM would find small areas without detail and extract white samples from those. My "Details, details" page shows various methods for this. On that ...

In this image, the light intensity varies, and so does the colour of the light.

I can (probably) explain that. I placed the map on the floor, near an East facing glass double door, at 8:00 AM, and then placed a incandescent lamp with its "back" towards the door.

So near the lamp the light was ...

Thanks for that - most helpful.

I've never used (and didn't even know about) -sparse-color

http://www.imagemagick.org/Usage/canvas/#sparse-color

which is clearly an excellent answer to my interpolation requirment!!

EDIT; the -sparse-color isn't working. I'm using
convert -version
Version ...

I would have a go at setting the whitepoint on the images before joining them and see what the result was. It may be easier dealing with the smaller images than the one large one?

That probably reduces the problem, but the lighting is non-uniform even on the sub-images (there are only3 sub images ...

I am currently preparing techniques to be used when visiting an archive
of historical documents, and will be taking photographs under some tight constraints.

I wish to capture some (old) maps. This will be done by taking multiple
overlapping images, and stitching them together. I have (with help ...

That's a very good basis for a solution to my problem.

Thank you.

BugBear

I wish to do something pretty simple;

I have an RGB image (let's call it a character, say "snoopy");

I wish to make an animation of small snoopy moving (sliding, really) across a large RGB background image, so a programmed sequence
of blits to successive (x,y) coordinates on the background will ...

I just ran this on a 4x3 grid of 2.5Mb JPEG, which make up a 9524x10405 pixel output file (28 Mb JPEG)

Last night, using the "obvious" "appends" to make rows (of tiff) then "append" the rows, this took around 20 minutes, and
thrashed the hard drive most cruelly.

Just now, with the perl script ...

For reasons of my own, I required a memory efficient montager.

I coded it around netpbm, especially pnmcat and it uses named pipelines (Posix FIFO's).

It only accepts JPEG and generates a PAM stream to stdout; typical usage would be, where BR is a row separator.

tess.pl tile0_0.jpg tile0_1.jpg ...

You are selecting one channel, with "-channel R".


That was my intent. I want a single (separated) channel. And I wanted it grayscale
(single byte samples).

But the result, as per -identify, and/or opening the output in GIMP is (still) RGB,
albeit RGB that "looks like" a single separated channel ...

I wanted to use convert as a CMYK colour separator, exploiting the LCMS engine.

But (a few trials later) I find that even trivial RGB separation is not behaving according to my understanding
of the documentation.

I'm working from here:

http://www.imagemagick.org/Usage/color_basics/#separate

Even ...

Horizontal concatenation (using streaming) is harder. You essentially need to open N images simultaneously to read one line from each image in that row to generate one line of output.


Yes, that's exactly what concat does. So you need an open FD and a line buffer for each input image. You would ...

Using some test data I had lying around, I came up with this (escaped for Unix shell)


convert \( half.c -depth 8 -blur 8x8 -resize '12.5%x12.5%' -negate \) \
\( half.m -depth 8 -blur 8x8 -resize '12.5%x12.5%' -negate \) \
\( half.y -depth 8 -blur 8x8 -resize '12.5%x12.5%' -negate \) \
\( half.k ...

Information on exactly what level it handles streaming is not provided


Sorry - it's so implicit, it's almost never mentioned. The main mode of working in netpbm, for sequential operations is to PIPE together (in Unix) multiple
commands. There's another implicit assumption. Since all the commands ...

As you are simply appending and concatenating you may have other options.
...

The problem is that while I have seen information on splitting up massive images into smaller pieces using 'streaming' methods, I have not seen information on taking a set of tile images and using streaming methods to ...