ImageMagick提取具有透明背景的非矩形区域 [英] ImageMagick exract non-rectangular region with transparent background

问题描述

根据以下问题的答案

例如，为提取的矩形区域的其余部分添加透明背景与黑色区域无关的图像。

解决方案

是的，我的ImageMagick脚本可以修改如下：

  infile = image.png
 inname =`convert -ping $ infile -format％tinfo：`
 OLDIFS = $ IFS 
 IFS = $'\ n'
 arr =（`convert $ infile + repage -blur 0x7 -auto-level -negate -t​​hreshold 2％-negate -t​​ype bilevel + write tmp.png \ 
 -define connected-components： verbose = true \ 
 -connected-components 8 \ 
 null：| tail -n +2 | sed's / ^ [] * //'`）
 num = $ {＃arr [*]} 
 IFS = $ OLDIFS 
 for（（i = 0; i< num;我++））; do 
 echo$ {arr [$ i]}
 color =`echo $ {arr [$ i]} | cut -d\ -f5` 
 bbox =`echo $ {arr [$ i]} | cut -d\ -f2` 
 echocolor = $ color; bbox = $ bbox
 if [$ color=gray（0）];然后
转换tmp.png -crop $ bbox + repage -fuzz 10％-trim + repage -alpha copy -channel a -negate + channel $ {inname} _ $ i.png 
 fi 
完成
  

以下结果是透明的，因此外部显示为白色。但是如果你下载它们，你会发现背景是透明的。

Based on the answer to the following question Programmatically divide scanned images into separate images right now I able to extract rectangular region.

Is it possible to modify the following ImageMagick script:

infile="image.png"
inname=`convert -ping $infile -format "%t" info:`
OLDIFS=$IFS
IFS=$'\n'
arr=(`convert $infile -blur 0x5 -auto-level -threshold 99% -type bilevel +write tmp.png \
-define connected-components:verbose=true \
-connected-components 8 \
null: | tail -n +2 | sed 's/^[ ]*//'`)
num=${#arr[*]}
IFS=$OLDIFS
for ((i=0; i<num; i++)); do
#echo "${arr[$i]}"
color=`echo ${arr[$i]} | cut -d\  -f5`
bbox=`echo ${arr[$i]} | cut -d\  -f2`
echo "color=$color; bbox=$bbox"
if [ "$color" = "gray(0)" ]; then
convert $infile -crop $bbox +repage -fuzz 10% -trim +repage ${inname}_$i.png
fi
done

to be able to extract non-rectangular region that exactly matches the black regions in the tmp.png:

For example, add a transparent background for the rest of the rectangular region of the extracted image that is not related to the black region.

解决方案

Yes, my ImageMagick script can be modified as follows:

infile="image.png"
inname=`convert -ping $infile -format "%t" info:`
OLDIFS=$IFS
IFS=$'\n'
arr=(`convert $infile +repage -blur 0x7 -auto-level -negate -threshold 2% -negate -type bilevel +write tmp.png \
-define connected-components:verbose=true \
-connected-components 8 \
null: | tail -n +2 | sed 's/^[ ]*//'`)
num=${#arr[*]}
IFS=$OLDIFS
for ((i=0; i<num; i++)); do
echo "${arr[$i]}"
color=`echo ${arr[$i]} | cut -d\  -f5`
bbox=`echo ${arr[$i]} | cut -d\  -f2`
echo "color=$color; bbox=$bbox"
if [ "$color" = "gray(0)" ]; then
convert tmp.png -crop $bbox +repage -fuzz 10% -trim +repage -alpha copy -channel a -negate +channel ${inname}_$i.png
fi
done

The following results are transparent, so show white for the outside. But if you download them, you will see that the background is transparent.

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