Hi Prahalad, Thank you for reviewing the change.
Yes we don't have any official Microsoft documentation today for BITMAPV2INFOHEADER & BITMAPV3INFOHEADER. We have only references to these undocumented DIB header types in http://fileformats.archiveteam.org/wiki/BMP , https://forums.adobe.com/message/3272950#3272950 & https://en.wikipedia.org/wiki/BMP_file_format I think that while BMP specification was getting enhanced Microsoft might have supported these formats but after that made BITMAPV4HEADER as officially supported format. Because of that we see that still some software like GIMP, Adobe Photoshop generate images with BITMAPV2INFOHEADER/ BITMAPV3INFOHEADER. Also all the official Microsoft documentation present as of now are from Windows SDK 2000 so we don't know what was the official journey of BMP specification pre 2000. Regards, Jay -----Original Message----- From: Prahalad Kumar Narayanan Sent: Wednesday, March 21, 2018 2:33 PM To: Philip Race; Jayathirth D V; 2d-dev Subject: RE: [OpenJDK 2D-Dev] [11] RFR JDK-7031957: DIB header of type BITMAPV2INFOHEADER & BITMAPV3INFOHEADER is not supported in BMPImageReader Hello Jay Good day to you. I looked into the code changes and they look good. Appreciate the links that you have posted on JBS. I see that - the only reference material on Bitmap V2/V3 Info Header header exists on Adobe Forums (https://forums.adobe.com/message/3272950#3272950) I could not find official reference from Microsoft describing the same. Just curious to know : If there was any reason behind not documenting these versions of image header. Thank you Have a good day Prahalad N. ----- Original Message ----- From: Phil Race Sent: Tuesday, March 20, 2018 9:57 PM To: Jayathirth D V; 2d-dev Subject: Re: [OpenJDK 2D-Dev] [11] RFR JDK-7031957: DIB header of type BITMAPV2INFOHEADER & BITMAPV3INFOHEADER is not supported in BMPImageReader In that case the patch is fine. -phil. On 03/20/2018 12:15 AM, Jayathirth D V wrote: HI Phil, Please find my observation: In case of DIB header type BITMAPINFOHEADER/ BITMAPV4HEADER/ BITMAPV5HEADER, Microsoft documentation(https://msdn.microsoft.com/en-us/library/dd183376(v=vs.85).aspx ) mentions that mask values are valid only when compression type is BI_BITFIELDS. When compression type is BI_RGB which ii no compression, Microsoft document mentions that 1) For 16 bpp : "The relative intensities of red, green, and blue are represented with five bits for each color component. The value for blue is in the least significant five bits, followed by five bits each for green and red. The most significant bit is not used.". So basically it should be RGB555. 2) For 32 bpp : "Each DWORD in the bitmap array represents the relative intensities of blue, green, and red for a pixel. The value for blue is in the least significant 8 bits, followed by 8 bits each for green and red. The high byte in each DWORD is not used". So basically it should be XRGB8888. This is why we have redMask = 0x7C00, greenMask = 0x3E0, blueMask = 0x1F in case of 16bpp and redMask = 0x00FF0000, greenMask = 0x0000FF00, blueMask = 0x000000FFfor 32bpp for all the three standard formats BITMAPINFOHEADER, BITMAPV4HEADER and BITMAPV5HEADER. Since BITMAPV2INFOHEADER & BITMAPV3INFOHEADER support falls in between that of other Microsoft documented DIB header types it is good that we follow the same approach in case of BITMAPV2INFOHEADER & BITMAPV3INFOHEADER also. Please let us know your inputs. Thanks, Jay From: Phil Race Sent: Monday, March 19, 2018 11:07 PM To: Jayathirth D V; 2d-dev Subject: Re: [OpenJDK 2D-Dev] [11] RFR JDK-7031957: DIB header of type BITMAPV2INFOHEADER & BITMAPV3INFOHEADER is not supported in BMPImageReader Since the principal addition of these formats is to add explicit fields for supporting the bitmasks for accessing R/G/B/A it seems odd to see there is code like this which ignores it when the data is uncompressed by using these hardcoded values : 456 if ((int)compression == BI_RGB) { 457 redMask = 0x7C00; 458 greenMask = 0x3E0; 459 blueMask = 0x1F; I do see that it seems likely you copied this from the 108/124 case but I'd like to see some proof that this is correct. -phil. On 03/14/2018 03:39 AM, Jayathirth D V wrote: Hello All, Please review the following solution in JDK11 : Bug : https://bugs.openjdk.java.net/browse/JDK-7031957 Webrev : http://cr.openjdk.java.net/~jdv/7031957/webrev.00/ Issue: If we try to read any BMP image of DIB header type BITMAPV2INFOHEADER/ BITMAPV3INFOHEADER, we get IOException mentioning the BMP image type in not yet implemented. Root cause: BMPImageReader doesn't support DIB header types BITMAPV2INFOHEADER/ BITMAPV3INFOHEADER we support only BITMAPCOREHEADER, BITMAPINFOHEADER, BITMAPV4HEADER & BITMAPV5HEADER. Solution: Many other tools like GIMP, Microsoft PowerPoint, IrfanView support BITMAPV2INFOHEADER & BITMAPV3INFOHEADER format BMP images. We can consider BITMAPV2INFOHEADER & BITMAPV3INFOHEADER header types having functionality in between that of BITMAPINFOHEADER & BITMAPV4HEADER. BITMAPINFOHEADER with type BITFIELDS & extra 4 bytes for alpha channel or First 56 bytes of BITMAPV4HEADER is nothing but BITMAPV3INFOHEADER. To support BITMAPV2INFOHEADER & BITMAPV3INFOHEADER we can use similar approach of what we are doing while decoding first 56 bytes under BITMAPV4HEADER. So I have added additional "if()" to do the same, we can merge decoding of BITMAPV2INFOHEADER & BITMAPV3INFOHEADER at the same place where we are decoding BITMAPV4HEADER but we need to add many branch conditions to follow that approach. Thanks, Jay
