What is not working for Grayscale? Looking at the code it will do
different things when you are passing Qt::red, Qt::blue, Qt::green.
It will not return a color image but a grayscale image of the
corresponding channel.
On 3/16/2018 2:08 PM, Jason H wrote:
Sent: Friday, March 16, 2018 at 9:12 AM
From: "Nikolai Tasev" <niko...@nand.bg>
To: "Jason H" <jh...@gmx.com>, "Interestqt-project.org"
<Interest@qt-project.org>
Subject: Re: [Interest] QImage::Format_Grayscale8 work working
Format_Indexed8 and Format_Grayscale8 both have 8bit per pixel. The
difference is that to convert from the 8bit pixel to RGB values
(QImage::pixel() method)
for Indexed8u you need to set the Palette for conversion and for
Grayscale8 you don't (it just assumes that R=G=B=gray value)
I am aware of that.
Are you trying to extract a channel from a multichannel image and put it
into a grayscale image? The code seems unnecessary complex
and inefficient for such a task. You just need to get the data pointer
and skip the uneeded channels and keep watch for the end of the row.
That assumes I be want to do the math for every Format. ARGB is easy, RGB888 is
not, etc. Pixel() alerts need to not care. Yes, I could use scan lines, but
then each format requires code. Which I haven't got time to write now.
Anyway, I be still believe my code is correct, and it's still not working.
On 3/15/2018 10:21 PM, Jason H wrote:
Given the following functions, I should be able to create a non-all black image
(assuming input is good)? The only success I have is using Indexed8
QHash<QRgb, qint32 (*)(QRgb)> colorFuncs {
{ Qt::red, qRed},
{ Qt::green, qGreen},
{ Qt::blue, qBlue},
{ Qt::gray, qGray},
};
QImage color8(const QImage &image, int channel) { // Channel is one of Qt::red
Qt::green Qt::blue or Qt::gray
QImage out(image.width(), image.height(), QImage::Format_Indexed8); //
Change to Format_Grayscale8, and get nothing
// for indexed8
QVector<QRgb> values;
values.reserve(256);
if (channel==Qt::gray) { for (int c=0; c<256; c++)
values.append(qRgb(c,c,c)); }
if (channel==Qt::red) { for (int c=0; c<256; c++)
values.append(qRgb(c,0,0)); }
if (channel==Qt::green){ for (int c=0; c<256; c++)
values.append(qRgb(0,c,0)); }
if (channel==Qt::blue) { for (int c=0; c<256; c++)
values.append(qRgb(0,0,c)); }
out.setColorTable(values);
// end for indexed8
int (*colorFunc)(QRgb rgb) = colorFuncs[channel];
for (int y=0; y < image.height(); y++) {
for (int x=0; x < image.width(); x++) {
out.setPixel(x,y, colorFunc(image.pixel(x,y)));
}
}
return out;
}
I'm not familar with Qt and Grayscale8... Anyone know what is going wrong?
_______________________________________________
Interest mailing list
Interest@qt-project.org
http://lists.qt-project.org/mailman/listinfo/interest
_______________________________________________
Interest mailing list
Interest@qt-project.org
http://lists.qt-project.org/mailman/listinfo/interest
