Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>This seems to work and produce not-all-black output. There may be a way to do it that doesn't involve a manual conversion to grayscale first, but at least it works!</p> <pre><code>static void WriteCCITTTiffWithCGImage_URL_(CGImageRef im, CFURLRef url) { // produce grayscale image CGImageRef grayscaleImage; { CGColorSpaceRef colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericGray); CGContextRef bitmapCtx = CGBitmapContextCreate(NULL, CGImageGetWidth(im), CGImageGetHeight(im), 8, 0, colorSpace, kCGImageAlphaNone); CGContextDrawImage(bitmapCtx, CGRectMake(0,0,CGImageGetWidth(im), CGImageGetHeight(im)), im); grayscaleImage = CGBitmapContextCreateImage(bitmapCtx); CFRelease(bitmapCtx); CFRelease(colorSpace); } // generate options for ImageIO. Man this sucks in C. CFMutableDictionaryRef options = CFDictionaryCreateMutable(kCFAllocatorDefault, 2, &amp;kCFTypeDictionaryKeyCallBacks, &amp;kCFTypeDictionaryValueCallBacks); { { CFMutableDictionaryRef tiffOptions = CFDictionaryCreateMutable(kCFAllocatorDefault, 1, &amp;kCFTypeDictionaryKeyCallBacks, &amp;kCFTypeDictionaryValueCallBacks); int fourInt = 4; CFNumberRef fourNumber = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &amp;fourInt); CFDictionarySetValue(tiffOptions, kCGImagePropertyTIFFCompression, fourNumber); CFRelease(fourNumber); CFDictionarySetValue(options, kCGImagePropertyTIFFDictionary, tiffOptions); CFRelease(tiffOptions); } { int oneInt = 1; CFNumberRef oneNumber = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &amp;oneInt); CFDictionarySetValue(options, kCGImagePropertyDepth, oneNumber); CFRelease(oneNumber); } } // write file CGImageDestinationRef idst = CGImageDestinationCreateWithURL(url, kUTTypeTIFF, 1, NULL); CGImageDestinationAddImage(idst, grayscaleImage, options); CGImageDestinationFinalize(idst); // clean up CFRelease(idst); CFRelease(options); CFRelease(grayscaleImage); } Nepheli:tmp ken$ tiffutil -info /tmp/output.tiff Directory at 0x1200 Image Width: 842 Image Length: 562 Bits/Sample: 1 Sample Format: unsigned integer Compression Scheme: CCITT Group 4 facsimile encoding Photometric Interpretation: "min-is-black" Orientation: row 0 top, col 0 lhs Samples/Pixel: 1 Number of Strips: 1 Planar Configuration: Not planar </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POProducing CCITT compressed TIFF from CGImage
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USuser96459
    1. USuser96459
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIs that Objective C or C++? It looks like a wierd combination. In C++ I don't think that compression 4 works. It gives uncompressed...
      singulars
      1. PO
      1. USBrian Postow
    2. COThe language you write in is not going to affect the behavior of the APIs. This is Objective-C. I'll rewrite it as pure C for you.
      singulars
      1. PO
      1. USuser96459
    3. COOkay, edited to pure C. It should compile as C++. CGImageDestination covers libtiff and passes the compression through unmolested. I found that I had to explicitly pass depth == 1 and a grayscale image to get it to work. If you google for libtiff and "CCITT Group 4" you'll see some people asking questions about it.
      singulars
      1. PO
      1. USuser96459
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload