Legacy ImageMagick Discussions Archive

Hi,

I have an image which is a lot of stips one under the other. So far I have split them into separate images.

convert  input.jpg  -crop 1648x128 +repage  out_%03d.png

next I recompose them using every third strip: ( it's actually the 3 RGB layers interleaved )

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convert out_234.png out_237.png out_240.png out_243.png -append out-collate.png

So firstly with that many images I want to do that automatically. Is that possible with IM6 or do I need to do that in a loop script calling convert.

Secondly the images have a few pixels of duplication, so I want to supply an y offset of fixed magnitude each time I collate a strip.

Now I know IM6 is amazingly powerful but parsing all the doc to find out how to do this is getting to look like a three year degree course.

Can someone shorten my pain by pointing me in the right direction, please?

Many thanks.

[EDIT] As requested: using ImageMagick 6.9.2-7 Q16 x86_64 Linux

Please always provide your IM version and platfom. In stead of using +append, you can use montage with -geometry -X+0 to get some overlap. See http://www.imagemagick.org/Usage/montage/#overlap. If that does not help, then please post a few of your images that you want to append to some free hosting service such as dropbox.com (public directory) and put the URLs here.

To handle the "every third strip", you probably need a script. How many strips per source image?

For speed, you can do things like this (in Windows BAT):

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convert input.jpg -crop 1648x128 +repage -delete %DEL_LIST% -append out-collate.png

For bash, you would have %(DEL_LIST).

Before do the convert, the script would set DEL_LIST to be 0,1,3,4,6,7,9,10 and so on.

I believe on bash it would be

del_list="0,1,3,4,6,7,9,10"

then to use it,

-delete $del_list

or perhaps

-delete "$del_list"

Not sure it should matter

Thanks, Fred. I'm hopeless at bash.

The job sounds quite simple. But, rather than creating all the slices, saving them as files, then reading every third one, it may be easier and quicker to do all the processing in a single convert.

If the OP puts up a source image, we may be able to advise better.

Thanks, I can create the list of numbers in bash and use a shell variable as suggested.

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list=`seq -s , 1 3 10`
echo $list
1,4,7,10

I was wondering whether fx can do that sort of thing.

Hmm, having trouble getting the list arg to work:

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convert  input.png  -crop 1648x128  +repage  -delete "$list"  -append  out_%03d.png

convert: geometry does not contain image `input.png' @ warning/transform.c/CropImage/716.

snibgo wrote:Thanks, Fred. I'm hopeless at bash.

The job sounds quite simple. But, rather than creating all the slices, saving them as files, then reading every third one, it may be easier and quicker to do all the processing in a single convert.

If the OP puts up a source image, we may be able to advise better.

I agree it's probably best done in one hit. But IM is as cryptic as hell so I like to do things in little bits, then get clever once it seems to work

It's the Juno Earth fly-by efb12 I'm playing with. They're rather large but if you'd rather have the image ::
http://www.msss.com/junocam_efb/efbimg.html

I expect the whole exercise will a single IM command at the end of it.

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convert  junocam_efb12.jpg -roll +0+3328  -crop 1648x9856 -delete "1,2,3"   junocam_efb12_roll.png

OK, the geometry thing is something else. I had rolled and cropped to get rid of all the dead wood and get a more managable file size. It looks OK in display or GIMP and file reports sensible dimensions etc but convert does not seem to want to work with it again afterwards

I've had this kind of thing with IM in the past, I think, can someone remind me what extra tweak it needs ?

try

-delete 1,2,3

no quotes

Note image indices start with 0, not 1

You may also want to add +repage after the crop to remove the virtual canvas.

yes thanks, I've found the missing +repage.

This is behaving sensibly now. I need three lists made by seq to skim out each colour plane,

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 list1=`seq -s , 1 3 76`
 list2=`seq -s , 2 3 76`
 list3=`seq -s , 0 3 76`

it works OK like this:

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 convert  junocam_efb12_roll.png  -crop 1648x128  +repage -delete "$list1,$list2"  -append efb12_collate.png

Now I need to lose the last 13 rows of each strip which are duped.but adding in another crop does not seem to make any difference

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convert  junocam_efb12_roll.png  -crop 1648x128  +repage -delete "$list,$list2" -crop 1648x115  +repage  -append efb12_collate.png

Perhaps I misunderstand what you are doing.

You should be able to delete the last 13 rows by:

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convert  junocam_efb12_roll.png  -crop 1648x128  +repage -delete "$list,$list2" -delete -1--13 -append efb12_collate.png

See http://www.imagemagick.org/Usage/basics/#list_ops

EDITED: Removed first crop concept, since I do not know how many good rows you have.

Thanks but it's not the strips I want to remove here, it's the lower 13 pixel rows of ALL the strips which remain after

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-delete "$list,$list2"

just before the final append.

OK this seems to do it. I could not work out why -crop didn't do it, but I was not providing the offsets.

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 convert  junocam_efb12_roll.png  -crop 1648x128  +repage -delete "$list,$list2" -crop 1648x115+0+13  +repage  -append efb12_collate.png

I actually need to do the roll and crop after the splicing , it was good enough to speed up processing while I debugged it though.

Now I just need to do the aoove three times with the different $list arguement and collate the the three 8 bit grayscales into a 24bit RGB.

Thanks for the help.

If your problem is getting crops that are not full size regions, seems to me that it would be better to initially crop your input image to a multiple of your crop sizes rather than trying to remove them at the end.

fmw42 wrote:If your problem is getting crops that are not full size regions, seems to me that it would be better to initially crop your input image to a multiple of your crop sizes rather than trying to remove them at the end.

No, it's in the other direction. I have wide, short ( y ) strips which have some ( 13ox ) duplication in y. So it makes sense to cut into strips and then remove a bit across the bottom of each strip. The line above seems to do the job.

My problem now is that there is an x shift from one strip to the next. This means that I need to compose the crop arguments using -fx and the image count n but it does not want to play. What is the correct way to go about this?

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 -crop 1648x115+'%[fx:n*5]'+13

convert: invalid argument for option `-crop': 1648x115+%[fx:n*5]+13 @ error/convert.c/ConvertImageCommand/1176.

thx.

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