QImage Class, loading an image results in different behaviour between debug and release

[R4P70R]

I have found the root of my image display problem after some investigations but I still don't understand if this is actually a bug.
My program is working fine in release but not really in debug sessions.

Here is the part. I load a 2048x2048 grayscale 8bits bmp image this way:

QImage image(":/v3_res.bmp");

Then if I verify the image format:

qDebug() << "image format is " << image.format();
qDebug() << "image size is " << image.byteCount();

Output from release:
image format is 3
image size is 4194304

Output from debug:
image format is 4
image size is 16777216

While this is actually the same image, the pixel format is not the same.

Tried this:
QImage image(2048,2048,QImage::Format_Indexed8);
image.load(":/v3_res.bmp", "BMP");
But it doesn't change format during debug.

Also tried this:
image = image.convertToFormat(QImage::Format_Indexed8);
which show an image but looks kinda strange because you see it was not read in the correct format first.

Image metadata looks correct (Windows report 8 Bits depth) and file size is 4'195'382 bytes

So I have 2 questions now:
Is this a bug?
Is there a way to force the format during the creation of the QImage with a filename?

Thank you for your answers

[VRonin]

• could you upload the file somewhere so we can test it?
• what version of Qt, compiler and OS are you using?

[R4P70R]

I upload it here
https://drive.google.com/file/d/0B8NvEIhEx_TfQTBVc3JYb3NjMHM/view?usp=sharing
File was found in png on internet, converted to 256-grayscale and saved to bitmap using XnView

I'm using
Qt 5.8.0 MinGW 32bit (mingw53_32)
MinGW 5.3.0 32bit
Windows 10 Pro 64 (v1703)

[R4P70R]

Just to update the issue, I tried the minimal code to load this image and it works now correctly everytime in debug too.. format 3 (QImage::Format_Indexed8) is reported for both.

The issue is probably coming from somewhere else but it will be very difficult to track it down now...
The code is exactly:
"
QImage image(":/v3_res.bmp");
qDebug() << "image format is " << image.format();
qDebug() << "image size is " << image.byteCount();
"
And I don't understand how it may be related to anything else in my software.

Still looking for a way to force this in a manual way for the moment.

[R4P70R]

Ok, I think a clean and rebuild of the whole project did the trick.

I always forget when I don't use it for sometimes. When something is doing weird with Qt you have to clean, qmake or rebuild to get everything in order.

I will tag this issue as solved !