Hi, Larry Gritz: Thank you so much for your help. I successfully ran the code on Linux and got what I want. The only problem is when running on Windows, the output is all black without any text. I guess it is due to the OpenImageIO binary library I used. So I was wondering if you could please take a look at it.
The OpenImageIO binary library I am using on Windows is downloaded from here <https://urldefense.proofpoint.com/v2/url?u=http-3A__jesnault.fr_website_wp-2Dcontent_uploads_OIIO-2Dinstall-2Dmsvc11-2Dx64.7z&d=DwIFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=XXy2-fXn17psA3p18bZUaPjQ7xX0HVz9zDgc_F0CCMc&s=r264H7-f1kWULEwvRNvCF4iCm2Eh1ZJ7YPjKzpDPYwU&e= > in this webpage <https://urldefense.proofpoint.com/v2/url?u=http-3A__jesnault.fr_website_how-2Dto-2Dbuild-2Dwindows-2Dimages-2Dlibraries_&d=DwIFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=XXy2-fXn17psA3p18bZUaPjQ7xX0HVz9zDgc_F0CCMc&s=iCu1OtJNTi82EdHi_1lId-kdQIogtxzTKSULtDtvcWE&e= >. I can correctly link it in Visual Studio 2015 but when running the statement ImageOutput::create("file_name.exr");, the program crashes with the following error message: I have no idea how to fix this problem. I guess the binary library files I downloaded have some problem because the above webpage says it is compiled for Visual Studio 2012 but I am using Visual Studio 2015. The instructions of building OpenImageIO from source are either not working ( https://urldefense.proofpoint.com/v2/url?u=https-3A__sites.google.com_site_openimageio_building-2Doiio-2Don-2Dwindows&d=DwIFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=XXy2-fXn17psA3p18bZUaPjQ7xX0HVz9zDgc_F0CCMc&s=uGh1rGb2DG9tLqQL8XydSsDTeGr7qzVikvQ68t2rVgs&e= ) or looks too daunting for me ( https://urldefense.proofpoint.com/v2/url?u=http-3A__jesnault.fr_website_how-2Dto-2Dbuild-2Dwindows-2Dimages-2Dlibraries_-3Flang-3Den&d=DwIFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=XXy2-fXn17psA3p18bZUaPjQ7xX0HVz9zDgc_F0CCMc&s=ajCPIbmNvOONZsMUliOCqyoFoIENFiUtf8oWDDveVlY&e= ), so what I'd like to ask is: if you (or anyone else) happen to have a compiled binary library of OpenImageIO for Windows 7 64-bit, could you please share that with me? Thanks a lot! Thank you again for teaching me how to render text. Best Regards Heng Zhou On Tue, Mar 21, 2017 at 1:11 PM, Larry Gritz <[email protected]> wrote: > On Mar 21, 2017, at 4:40 AM, Heng Zhou <[email protected]> wrote: > > Thank you for the interesting post. I happen to be working on a project in > which I need to composite a text onto a background image. But both the text > and background image are generated by C++ code, so I hope I can write a few > lines of code to do the same job as what oiiotool does in your post. I have > no idea how. Could you (or any other nice people) please share a C++ > snippet with me? I don't need a shadowed text; just displaying it on the > image I generated would suffice. Thanks a lot! > > > > Sure! > > I'm just doing this off the top of my head, so please double check against > the docs, but this should point you there. > > #include <OpenImageIO/imagebuf.h> > #include <OpenImageIO/imagebufalgo.h> > using namespace OIIO; > ... > > To load a background image: > > ImageBuf bg ("background.tif"); > > Or to *wrap* an existing buffer (the ImageBuf won't allocate or own the > pixel memory): > > unsigned char image[xres*yres*channels]; > ImageSpec spec (xres, yres, channels, TypeDesc::UINT8); > ImageBuf bg (spec, image); > > Alternately, to *copy* from an existing buffer (with the ImageBuf > allocating and managing its own pixel memory): > > ImageBuf bg (spec); > bg.set_pixels (ROI(0,xres,0,yres,0,1,0,channels), TypeDesc::UINT8, > image); > > To add text to your buffer: > > float textcolor[3] = { 1, 1, 1 }; // MUST be at least as long as the > number of channels! > ImageBufAlgo::render_text (bg, 50 /* x */, 100 /* y */, > "Hello, world!" /* text to draw */, > 32 /* font size */, "" /* font name, empty > for default */, > textcolor); > > And then to save the image to disk: > > bg.set_write_format (TypeDesc::UINT8); > bg.write ("output.tif"); > > Or, if you had "wrapped" an image, the text will already be in your > original buffer. > > Or, if you *copied* the image, you can copy out again like this: > > bg.get_pixels (ROI(0,xres,0,yres,0,1,0,channels), TypeDesc::UINT8, > image); > > > Does that answer your question? > > > > On Tue, Mar 21, 2017 at 2:00 AM, Larry Gritz <[email protected]> wrote: > >> Let's see if this comes through the mail list with images intact. If not, >> I'll make it into a wiki page or something. >> >> --- >> >> Let's say you have a text image, white on black, and you want to >> composite it over an existing background image. Let's quickly generate one >> to have it as an example: >> >> $ oiiotool -create 128x96 3 -text:x=20:y=50:size=32:color=1,0,0 >> "Hello" -d uint8 -o text.tif >> >> <text.png> >> >> And let's make an RGBA file for our background using something from our >> testsuite: >> >> $ cp tahoe-tiny.tif ./bg.tif >> >> <bg.png> >> >> Now, we could naively composite it: >> >> $ oiiotool text.tif bg.tif --over -o comp.tif >> *oiiotool ERROR: over : images must have alpha channels* >> >> Oops. Well, adding alpha to the background would be easy, >> >> oiiotool ... bg.tif -ch R,G,B,A=1.0 ... >> >> But what about the foreground? >> >> Well, if we really were just using oiiotool to make the text in the first >> place, we could have given it an alpha channel: >> >> $ oiiotool -create *128x96 4 *-text:x=20:y=50:size=32*:color=1,0,0,1* >> "Hello" -d uint8 -o textrgba.tif >> >> But let's suppose for a minute that we didn't have that luxury, we have >> an RGBA image of text and that's that. We can construct an alpha channel >> from the luminance, then thresholding it, like this, step by step (first, >> an invalid command line that explains, then a fully valid command line): >> >> oiiotool text.tif # read input >> --dup # duplicate it on the stack >> --chsum:weight=.2126,.7152,.0722 # compute luminance as >> single channel >> --mulc 20 # multiply it... >> --clamp:min=0:max=1 # ...and clamp to threshold >> --chappend # mash the original RGB with the >> luminance-computed alpha >> --chnames R,G,B,A # make sure that new channel has the >> right name >> bg.tif # read the background >> --ch R,G,B,A=1.0 # add an alpha channel to the backgound >> (opaque) >> --over # composite >> -o comp1.tif # output >> >> $ oiiotool text.tif --dup --chsum:weight=.2126,.7152,.0722 --mulc 20 >> --clamp:min=0:max=1 --chappend -chnames R,G,B,A bg.tif -ch >> R,G,B,A=1.0 --over -o comp1.tif >> >> The purpose of the --mulc and --clamp is so that a dimmer text color >> (less than luminance 1.0) won't make a semi-transparent alpha and show the >> background color through the text. >> >> <comp1.png> >> >> This is fairly nice, but a little naive about the text readability. What >> we really want is a bit of a blurred drop shadow, black rim around the >> letters, for better visibility against light backgrounds. So let's add a >> blur to the alpha we are generating, thus making the alpha image extend >> past the edges of the letters themselves to suppress part of the background: >> >> $ oiiotool text.tif --dup --chsum:weight=.2126,.7152,.0722 *--blur >> 5x5 *--mulc 20 --clamp:min=0:max=1 --chappend -chnames R,G,B,A bg.tif >> -ch R,G,B,A=1.0 --over -o comp2.tif >> >> <comp2.png> >> >> Voilà! Much nicer! Adjust the blur size and mulc threshold to suit your >> taste. >> >> >> >> -- >> Larry Gritz >> [email protected] >> >> >> >> _______________________________________________ >> Oiio-dev mailing list >> [email protected] >> https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.openimageio.org_listinfo.cgi_oiio-2Ddev-2Dopenimageio.org&d=DwIFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=XXy2-fXn17psA3p18bZUaPjQ7xX0HVz9zDgc_F0CCMc&s=Hd0yDoQco-n-nchovBIwrYc8Ltg429M_AosmjJJtY2w&e= >> >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.openimageio.org_listinfo.cgi_oiio-2Ddev-2Dopenimageio.org&d=DwMFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=euk9A4Ibxbdf6xWtliyUXHguHMD7O_gAzN3HZ6km25E&s=I64wq-2NHLavZXU1sdfiiXSdK59wX0HuUtIxnG4WhD0&e=> >> >> > _______________________________________________ > Oiio-dev mailing list > [email protected] > https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.openimageio.org_listinfo.cgi_oiio-2Ddev-2Dopenimageio.org&d=DwIFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=XXy2-fXn17psA3p18bZUaPjQ7xX0HVz9zDgc_F0CCMc&s=Hd0yDoQco-n-nchovBIwrYc8Ltg429M_AosmjJJtY2w&e= > > > > -- > Larry Gritz > [email protected] > > > > _______________________________________________ > Oiio-dev mailing list > [email protected] > https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.openimageio.org_listinfo.cgi_oiio-2Ddev-2Dopenimageio.org&d=DwIFaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=yN_mtgnvh2k3WD8QIZam9tbZUPHJMoZc_18KfiSrxx0&m=XXy2-fXn17psA3p18bZUaPjQ7xX0HVz9zDgc_F0CCMc&s=Hd0yDoQco-n-nchovBIwrYc8Ltg429M_AosmjJJtY2w&e= > > >
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