Supporting 16 bit images with Qt

[SachinBhat]

Hi,

We have developed a GUI application for loading images to our embedded platform. We need to load 16 bit images from tiff file format. The application uses 32 bit version of Qt 5.12 currently. I am able to load the tiff image in format 25. But this stores pixels in the form of 64 bit word which I cannot access as our application is 32 bit.

I got to know that qt supports 16 bit grayscale images which is okay for us as format 28 is supported in version 5.13. I can port our application to latest one.

I need clarification regarding format 28. Will it automatically convert a 48 bit rgb image to 16 bit? if yes, could you please suggest a way to do it?

Thanks
Sachin

[jsulm]

@SachinBhat said in Supporting 16 bit images with Qt:

uint16 p = reinterpret_cast<uint16>(image.scanLine());

const uint16 *p = reinterpret_cast<const uint16*>(image.scanLine());

should do...

[SachinBhat]

Also, If there is any way I can get the R G and B components of the 16 bit image in 32 bit version of application, then it would make it much easier for me

Thanks
Sachin

[SachinBhat]

QImage::Format_Grayscale16 28 The image is stored using an 16-bit grayscale format. (added in Qt 5.13)
QImage::Format_RGBX64 25 The image is stored using a 64-bit halfword-ordered RGB(x) format (16-16-16-16). This is the same as the Format_RGBA64 except alpha must always be 65535. (added in Qt 5.12)
QImage::Format_RGBA64 26 The image is stored using a 64-bit halfword-ordered RGBA format (16-16-16-16). (added in Qt 5.12)
QImage::Format_RGBA64_Premultiplied 27 The image is stored using a premultiplied 64-bit halfword-ordered RGBA format (16-16-16-16). (added in Qt 5.12)

The formats currently supported in Qt for 16 bit

Thanks
Sachin

[mvuori]

Nobody is supposed to know what formats 25 and 28 are.... Qt has symbol to represent formats.

But QImage has bits() and you can read them anyway you like - just get larger chunks for each pixel and its component.

[SachinBhat]

I use scanLine() to get the pointer of the particular line. But i get a uint08 * pointer. However it would be easy to get a uint16* pointer for processing. Any way to achieve this?

[jsulm]

@SachinBhat said in Supporting 16 bit images with Qt:

Any way to achieve this?

A simple cast of the pointer:

uint16 *p = reinterpret_cast<uint16*>(image.scanLine());

[SachinBhat]

This gives me error

int WaveFormWindow::quantize(QImage const &src, int bitDepth, QImage *dst)
{
uint08 mask;
uint08 orMask;
uint08 shift;

uint16 mask1, orMask1;
int minHeight = MIN(dst->height(),src.height());
int minWidth = MIN(dst->width(),src.width());
QImage image = src;

uint16 *p = reinterpret_cast<uint16*>(image.scanLine());

}

error: const_cast from 'const uchar *' (aka 'const unsigned char *') to 'uint16 *' (aka 'unsigned short *') is not allowed

I am not able to cast uint08 ptr to uint16 ptr. Please help

Thanks
in advance

Regards
Sachin

[jsulm]

@SachinBhat said in Supporting 16 bit images with Qt:

uint16 p = reinterpret_cast<uint16>(image.scanLine());

const uint16 *p = reinterpret_cast<const uint16*>(image.scanLine());

should do...

[SachinBhat]

Thank you very much for your support