Conversion from TMat to TBitmap

[tonbo01]

Hi. I have a similar question.
I'm using Delphi 11.3 and Delphi-OpenCV4.7.
I would like to perform a fast conversion from TMat to TBitmap with minimal steps.
Please advise me.

I am not using OpenCV 2.4.

Declare the variables as follows:
var
frame: TMat;
framebitmap: TBitmap;
It would be great if I could do something like:
Mat2Bitmap(frame, framebitmap);

[tonbo01]

Hi, I tried using
imencode('.bmp', frame, framebitmap); e.t.c.
But it seems that 'imencode' is undefined.
When I add {$I imgcodecs.inc}, I get a lot of compilation errors.
Is there any way to use imencode for the purpose mentioned above?
If it's possible, I would be happy to provide you with a sample code.
Thanks.

[Laex]

function MatToBitmap(img: TMat): Vcl.Graphics.TBitmap;
var
bmp: Vcl.Graphics.TBitmap;
i : Integer;
data: pByte;
pb: pByte;
begin
bmp := Vcl.Graphics.TBitmap.Create;
bmp.Width := img.cols;
bmp.Height := img.rows;
case img.elemSize * 8 of
8:
bmp.PixelFormat := pf8bit;
16:
bmp.PixelFormat := pf16bit;
24:
bmp.PixelFormat := pf24bit;
32:
bmp.PixelFormat := pf32bit;
End;
data := Pointer(img.data);
for i := 0 to img.rows - 1 do
begin
pb := bmp.Scanline[i];
move(data[i * img.cols * img.elemSize], pb[0], img.cols * img.elemSize);
End;
Result := bmp;
end;

[tonbo01]

Hi,
It worked successfully.
I have achieved my goal.
Thank you very much.
I'm not very familiar with OpenCV, so please teach me.
Is 'imencode' not usable in this case?
(Usable. Not usable)
I would like to make use of it since you kindly created it for oures.

[Laex]

'imencode' is a nice function with many possibilities, but it creates the image itself in the given encoding (RAW) with no additional overhead. For example, the image body itself must be placed inside a TBitmap component in order to use it in your program. Thus, the TBitmap placement algorithm will be different from TJPEG placement. In each case, you will need to manually configure the properties of the component. Some features of image encoding are not supported by vcl.graphics components.
If you are going to use the mat->, it makes sense to write utility functions for the transformation, taking into account the limitations of Delphi.

By the way, it is more convenient to store a RAW image in a database or send it over the network.

[tonbo01]

Hi,
Thank you for the detailed explanation.
I now understand the limitations of vcl.graphics.
However, I think vcl.graphics supports bitmap.
In that case, is it possible to use imencode to convert mat->bitmap? (yes, No)
I have been trying various code with imencode to check, but I couldn't verify it due to compile errors.

In the future, I will save images to the database.
I will use Raw images for that purpose.
Thank you.

[Laex]

In that case, is it possible to use imencode to convert mat->bitmap? (yes, No)
Yes
mat-> and then put inside vcl.graphics.TBitmap

[tonbo01]

Thank you for your response.
'Yes', as you mentioned, I attempted to convert TMat to TBitmap, taking reference from imgcodecs.inc.

var
mat, decoded_mat : TMat;
bmp : TBitmap;
bmpImageData : vector;

// imencode: TMat -> vector
imencode('.bmp', mat, bmpImageData);

// And I also tried the reverse:
// imdecode: vector -> TMat
decoded_mat := imdecode(bmpImageData, IMREAD_COLOR);

These conversions worked well.
I believe to achieve TMat -> TBitmap, I need to perform bmpImageData -> bmp, but I haven't been successful in doing so.
Thank you.

[tonbo01]

vector＜uchar＞

[Laex]

// ------- Definitions from OpenCV 4.8
const
IMWRITE_JPEG_SAMPLING_FACTOR = 7;
const
IMWRITE_JPEG_SAMPLING_FACTOR_411 = $411111;
// -------
var
img: TMat := imread('result.png');
Var
param: vector < int >;
param.push_back(IMWRITE_JPEG_SAMPLING_FACTOR);
param.push_back(IMWRITE_JPEG_SAMPLING_FACTOR_411);
Var
jpeg: vector < uchar >;
imencode('.jpg', img, jpeg, param);
Var
F: TFileStream := TFileStream.Create('result.jpg', fmCreate);
WriteLn(jpeg.size);
F.Write(jpeg.data^, jpeg.size * SizeOf(uchar));
F.Free;

[tonbo01]

Thank you for your polite response..

I was able to do it with jpeg.pT(0)^ .

[Laex]

Yes! And it is right!
Now I'm moving to version 4.8. Added new code.
jpeg.data is from the new code

[tonbo01]

Thank you very much.
I'm glad that this is the only place that supports the latest OpenCV.

[Laex]

unit cv.utils;

function BmpToMat(const Bitmap: TBitmap; out M: TMat): Boolean;
function MatToBmp(const M: TMat; out Bitmap: TBitmap; const PixelFormat: TPixelFormat = pfDevice): Boolean;

[tonbo01]

Dear Laex, I had not checked in for a while. Thank you very much for your response. I am deeply grateful for your assistance. Sincerely, Tonbo From: Laentir Valetov ***@***.***> Sent: Monday, November 4, 2024 11:35 PM To: Laex/Delphi-OpenCV-Class ***@***.***> Cc: tonbo01 ***@***.***>; Author ***@***.***> Subject: Re: [Laex/Delphi-OpenCV-Class] Conversion from TMat to TBitmap (Discussion #35) unit cv.utils; function BmpToMat(const Bitmap: TBitmap; out M: TMat): Boolean; function MatToBmp(const M: TMat; out Bitmap: TBitmap; const PixelFormat: TPixelFormat = pfDevice): Boolean; — Reply to this email directly, view it on GitHub <#35 (comment)> , or unsubscribe <https://github.com/notifications/unsubscribe-auth/A6N5BORTOJ4EB7PT3JEDTSDZ66AZJAVCNFSM6AAAAABREMVRH2VHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTCMJUGM2DMNI> . You are receiving this because you authored the thread.Message ID: ***@***.***>