OpenCV is not relevant in this case, that was just background that I probably didn't need to include.
I'm generating an image buffer, saving it as PNG through UIImage, then generating it again, and comparing it to the UIImage bytes I get by opening the previously-saved image. I'm not specifying anything other than device RGB color space when I create the CGBitmapContext I use to generate the image buffer. > On Nov 16, 2017, at 19:27 , Alex Zavatone <z...@mac.com> wrote: > > Before looking into OCV, my wild guess is that it may have to do with the > colorspace of the image. What are you setting it to? Profile Name: sRGB > IEC61966-2.1? > > >> On Nov 16, 2017, at 8:31 PM, Rick Mann <rm...@latencyzero.com> wrote: >> >> I'm trying to write a unit test for some code I wrote that generates one >> image from another. In the main app, the source data comes from Open CV as a >> buffer of 3 byte-per-pixel elements. My code generates a CGImage. In the >> unit test, I load a saved version of one of those images from a PNG file to >> UIImage, get at the buffer, pass it to my code, and then compare the result >> to a saved version of that same output. >> >> The saved version is a PNG. I load that, and then get the data buffer using >> >> let fiData = fi.dataProvider?.data as Data? >> >> I do a similar thing with the generated CGImage. Then I compare the two >> buffers, byte by byte. They are similar, but contain differences (sometimes >> more than I would expect). But if I save both as PNG and look at them in >> Preview they look identical. >> >> My guess is something's happening somewhere with color correction. In my >> code, I make a CG(bitmap)Context, specifying device RGB color space (should >> that be generic?). I don't really know what happens to the PNGs I save and >> load. >> >> Is there a way to ensure the bytes in the buffer are compressed and >> decompressed exactly as written? >> >> -- >> Rick Mann >> rm...@latencyzero.com >> >> >> _______________________________________________ >> >> Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) >> >> Please do not post admin requests or moderator comments to the list. >> Contact the moderators at cocoa-dev-admins(at)lists.apple.com >> >> Help/Unsubscribe/Update your Subscription: >> https://lists.apple.com/mailman/options/cocoa-dev/zav%40mac.com >> >> This email sent to z...@mac.com > -- Rick Mann rm...@latencyzero.com _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
