Cygwin Tesseract运行时错误：pixReadMemPng中的错误：函数不存在

我在Cygwin上创建了Tesseract 3.04.01。它可以识别.bmp文件，但无法识别.png文件：

$ tesseract.exe testing/phototest.png output Tesseract Open Source OCR Engine v3.04.01 with Leptonica Error in pixReadMemPng: function not present Error in pixReadMem: png: no pix returned Error during processing. $tesseract.exe测试/phototest.png输出 Tesseract开源OCR引擎v3.04.01，带有Leptonica pixReadMemPng中出错：函数不存在 pixReadMem中出错：png:未返回任何pix 处理过程中出错。

---

我以为leptopnica增加了对png的支持？

经过进一步挖掘，结果证明leptopnica更像是libpng和libtiff等标准库的包装器，如果找不到图像类型的库，它将自动禁用对图像类型的支持

它在运行

/configure

时给了我这个消息：

checking for png_read_png in -lpng... no 之后，它最终使用PNG支持构建，给出以下消息：

checking for png_read_png in -lpng... yes

由于某种原因，的链接顺序在Makefile-

-lpng-lz

中混淆，这导致链接liblept.la失败，原因如下：

png.c:(.text+0x13ab): undefined reference to `crc32'

我唯一能解决这个问题的方法是运行

make V=1

（详细模式）查看实际的命令，它是：

make[2]: Entering directory '/home/sasho/leptonica-1.73/src'
/bin/sh ../libtool  --tag=CC   --mode=link gcc  -g -O2 -no-undefined -version-info 5:0:0 -Wl,--as-needed -L/usr/local/lib -o liblept.la -rpath /usr/local/lib adaptmap.lo affine.lo affinecompose.lo arrayaccess.lo bardecode.lo baseline.lo bbuffer.lo bilateral.lo bilinear.lo binarize.lo binexpand.lo binreduce.lo blend.lo bmf.lo bmpio.lo bmpiostub.lo bootnumgen1.lo bootnumgen2.lo boxbasic.lo boxfunc1.lo boxfunc2.lo boxfunc3.lo boxfunc4.lo bytearray.lo ccbord.lo ccthin.lo classapp.lo colorcontent.lo coloring.lo colormap.lo colormorph.lo colorquant1.lo colorquant2.lo colorseg.lo colorspace.lo compare.lo conncomp.lo convertfiles.lo convolve.lo correlscore.lo dewarp1.lo dewarp2.lo dewarp3.lo dewarp4.lo dnabasic.lo dwacomb.2.lo dwacomblow.2.lo edge.lo encoding.lo enhance.lo fhmtauto.lo fhmtgen.1.lo fhmtgenlow.1.lo finditalic.lo flipdetect.lo fliphmtgen.lo fmorphauto.lo fmorphgen.1.lo fmorphgenlow.1.lo fpix1.lo fpix2.lo gifio.lo gifiostub.lo gplot.lo graphics.lo graymorph.lo grayquant.lo grayquantlow.lo heap.lo jbclass.lo jp2kheader.lo jp2kheaderstub.lo jp2kio.lo jp2kiostub.lo jpegio.lo jpegiostub.lo kernel.lo leptwin.lo libversions.lo list.lo map.lo maze.lo morph.lo morphapp.lo morphdwa.lo morphseq.lo numabasic.lo numafunc1.lo numafunc2.lo pageseg.lo paintcmap.lo parseprotos.lo partition.lo pdfio1.lo pdfio1stub.lo pdfio2.lo pdfio2stub.lo pix1.lo pix2.lo pix3.lo pix4.lo pix5.lo pixabasic.lo pixacc.lo pixafunc1.lo pixafunc2.lo pixalloc.lo pixarith.lo pixcomp.lo pixconv.lo pixlabel.lo pixtiling.lo pngio.lo pngiostub.lo pnmio.lo pnmiostub.lo projective.lo psio1.lo psio1stub.lo psio2.lo psio2stub.lo ptabasic.lo ptafunc1.lo ptra.lo quadtree.lo queue.lo rank.lo rbtree.lo readbarcode.lo readfile.lo recogbasic.lo recogdid.lo recogident.lo recogtrain.lo regutils.lo rop.lo ropiplow.lo roplow.lo rotate.lo rotateam.lo rotateamlow.lo rotateorth.lo rotateshear.lo runlength.lo sarray.lo scale.lo scalelow.lo seedfill.lo seedfilllow.lo sel1.lo sel2.lo selgen.lo shear.lo skew.lo spixio.lo stack.lo stringcode.lo sudoku.lo textops.lo tiffio.lo tiffiostub.lo utils.lo viewfiles.lo warper.lo watershed.lo webpio.lo webpiostub.lo writefile.lo zlibmem.lo zlibmemstub.lo  -lz -lpng       

然后，我执行了与当前目录相同的命令（从

/src

，否则它将不起作用），但在最后附加了另一个

-lz

，这使它成功。之后，我重新运行make，它继续构建图书馆的其余部分

cd src
/bin/sh ../libtool  --tag=CC   --mode=link gcc  -g -O2 -no-undefined -version-info 5:0:0 -Wl,--as-needed -L/usr/local/lib -o liblept.la -rpath /usr/local/lib adaptmap.lo affine.lo affinecompose.lo arrayaccess.lo bardecode.lo baseline.lo bbuffer.lo bilateral.lo bilinear.lo binarize.lo binexpand.lo binreduce.lo blend.lo bmf.lo bmpio.lo bmpiostub.lo bootnumgen1.lo bootnumgen2.lo boxbasic.lo boxfunc1.lo boxfunc2.lo boxfunc3.lo boxfunc4.lo bytearray.lo ccbord.lo ccthin.lo classapp.lo colorcontent.lo coloring.lo colormap.lo colormorph.lo colorquant1.lo colorquant2.lo colorseg.lo colorspace.lo compare.lo conncomp.lo convertfiles.lo convolve.lo correlscore.lo dewarp1.lo dewarp2.lo dewarp3.lo dewarp4.lo dnabasic.lo dwacomb.2.lo dwacomblow.2.lo edge.lo encoding.lo enhance.lo fhmtauto.lo fhmtgen.1.lo fhmtgenlow.1.lo finditalic.lo flipdetect.lo fliphmtgen.lo fmorphauto.lo fmorphgen.1.lo fmorphgenlow.1.lo fpix1.lo fpix2.lo gifio.lo gifiostub.lo gplot.lo graphics.lo graymorph.lo grayquant.lo grayquantlow.lo heap.lo jbclass.lo jp2kheader.lo jp2kheaderstub.lo jp2kio.lo jp2kiostub.lo jpegio.lo jpegiostub.lo kernel.lo leptwin.lo libversions.lo list.lo map.lo maze.lo morph.lo morphapp.lo morphdwa.lo morphseq.lo numabasic.lo numafunc1.lo numafunc2.lo pageseg.lo paintcmap.lo parseprotos.lo partition.lo pdfio1.lo pdfio1stub.lo pdfio2.lo pdfio2stub.lo pix1.lo pix2.lo pix3.lo pix4.lo pix5.lo pixabasic.lo pixacc.lo pixafunc1.lo pixafunc2.lo pixalloc.lo pixarith.lo pixcomp.lo pixconv.lo pixlabel.lo pixtiling.lo pngio.lo pngiostub.lo pnmio.lo pnmiostub.lo projective.lo psio1.lo psio1stub.lo psio2.lo psio2stub.lo ptabasic.lo ptafunc1.lo ptra.lo quadtree.lo queue.lo rank.lo rbtree.lo readbarcode.lo readfile.lo recogbasic.lo recogdid.lo recogident.lo recogtrain.lo regutils.lo rop.lo ropiplow.lo roplow.lo rotate.lo rotateam.lo rotateamlow.lo rotateorth.lo rotateshear.lo runlength.lo sarray.lo scale.lo scalelow.lo seedfill.lo seedfilllow.lo sel1.lo sel2.lo selgen.lo shear.lo skew.lo spixio.lo stack.lo stringcode.lo sudoku.lo textops.lo tiffio.lo tiffiostub.lo utils.lo viewfiles.lo warper.lo watershed.lo webpio.lo webpiostub.lo writefile.lo zlibmem.lo zlibmemstub.lo  -lz -lpng -lz      
cd -
make

---

出现上述错误时，可能是在编译和安装leptonica之前没有安装libpng-devel。你可以试试

yum安装libpng-devel

然后编译并安装leptonica

细锥虫/
澄清
/配置
制作
安装

---

这是我的centos7上的工作。

为什么不使用标准的

libpng16-devel

软件包进行编译，而不是自己构建？。注：cygwin还有一个tesseract 3.04.01软件包。@matzeri，因为我不知道从哪里获得它。我不知道输入什么命令才能得到它。没有

apt get

。标准工具：使用Setup

https://cygwin.com/cygwin-ug-net/setup-net.html#setup-软件包

我在libpng安装文档中添加了一个关于“常见链接失败”的部分。除其他事项外，它还提到需要以正确的顺序使用“-lpng-lz”。

cd src
/bin/sh ../libtool  --tag=CC   --mode=link gcc  -g -O2 -no-undefined -version-info 5:0:0 -Wl,--as-needed -L/usr/local/lib -o liblept.la -rpath /usr/local/lib adaptmap.lo affine.lo affinecompose.lo arrayaccess.lo bardecode.lo baseline.lo bbuffer.lo bilateral.lo bilinear.lo binarize.lo binexpand.lo binreduce.lo blend.lo bmf.lo bmpio.lo bmpiostub.lo bootnumgen1.lo bootnumgen2.lo boxbasic.lo boxfunc1.lo boxfunc2.lo boxfunc3.lo boxfunc4.lo bytearray.lo ccbord.lo ccthin.lo classapp.lo colorcontent.lo coloring.lo colormap.lo colormorph.lo colorquant1.lo colorquant2.lo colorseg.lo colorspace.lo compare.lo conncomp.lo convertfiles.lo convolve.lo correlscore.lo dewarp1.lo dewarp2.lo dewarp3.lo dewarp4.lo dnabasic.lo dwacomb.2.lo dwacomblow.2.lo edge.lo encoding.lo enhance.lo fhmtauto.lo fhmtgen.1.lo fhmtgenlow.1.lo finditalic.lo flipdetect.lo fliphmtgen.lo fmorphauto.lo fmorphgen.1.lo fmorphgenlow.1.lo fpix1.lo fpix2.lo gifio.lo gifiostub.lo gplot.lo graphics.lo graymorph.lo grayquant.lo grayquantlow.lo heap.lo jbclass.lo jp2kheader.lo jp2kheaderstub.lo jp2kio.lo jp2kiostub.lo jpegio.lo jpegiostub.lo kernel.lo leptwin.lo libversions.lo list.lo map.lo maze.lo morph.lo morphapp.lo morphdwa.lo morphseq.lo numabasic.lo numafunc1.lo numafunc2.lo pageseg.lo paintcmap.lo parseprotos.lo partition.lo pdfio1.lo pdfio1stub.lo pdfio2.lo pdfio2stub.lo pix1.lo pix2.lo pix3.lo pix4.lo pix5.lo pixabasic.lo pixacc.lo pixafunc1.lo pixafunc2.lo pixalloc.lo pixarith.lo pixcomp.lo pixconv.lo pixlabel.lo pixtiling.lo pngio.lo pngiostub.lo pnmio.lo pnmiostub.lo projective.lo psio1.lo psio1stub.lo psio2.lo psio2stub.lo ptabasic.lo ptafunc1.lo ptra.lo quadtree.lo queue.lo rank.lo rbtree.lo readbarcode.lo readfile.lo recogbasic.lo recogdid.lo recogident.lo recogtrain.lo regutils.lo rop.lo ropiplow.lo roplow.lo rotate.lo rotateam.lo rotateamlow.lo rotateorth.lo rotateshear.lo runlength.lo sarray.lo scale.lo scalelow.lo seedfill.lo seedfilllow.lo sel1.lo sel2.lo selgen.lo shear.lo skew.lo spixio.lo stack.lo stringcode.lo sudoku.lo textops.lo tiffio.lo tiffiostub.lo utils.lo viewfiles.lo warper.lo watershed.lo webpio.lo webpiostub.lo writefile.lo zlibmem.lo zlibmemstub.lo  -lz -lpng -lz      
cd -
make