function JpegLosslessTransform2(const FileName: WideString; Transform: TIEJpegTransform; UpdateEXIF: Boolean = True; ClearReadOnly: Boolean = False): boolean; overload;
function JpegLosslessTransform2(const FileName: WideString; Transform: TIEJpegTransform; GrayScale: boolean; CopyMarkers: TIEJpegCopyMarkers; CutRect: TRect; UpdateEXIF: Boolean = True; ClearReadOnly: Boolean = False): boolean; overload;
function JpegLosslessTransform2(const FileName: WideString; RotateAngle: Integer; UpdateEXIF: Boolean = True): boolean; overload;
function JpegLosslessTransform2(const FileName: WideString; Direction: TFlipDir; UpdateEXIF: Boolean = True): boolean; overload;
Losslessly rotates, flips or crops (cuts) a JPEG file. Same as JpegLosslessTransform
, but the source file is overwritten with the transformed image.
|Parameter ||Description |
|FileName ||The full path and filename of the file to transform |
|Transform ||The transformation to perform |
|GrayScale ||True force grayscale output |
|CopyMarkers ||How comments and markers (e.g. IPTC info) should be copied (Default: jcCopyAll) |
|CutRect ||Specifies the rectangle to retain when Transform = jtCut |
|UpdateEXIF ||Updates the EXIF thumbnail and orientation tags |
|ClearReadOnly ||If False and the file is marked Read-Only, conversion will fail |
Returns false if the operation failed.
- Rotation direction is the opposite to standard ImageEn Rotate
. jtRotate90 means rotate 90° clockwise
- With RotateAngle
overload, RotateAngle is a standard ImageEn rotation angle, e.g. 90 means rotate 90° counter-clockwise
. Values other than -90, 90, 180, -180, 270 and -270 are ignored
Whenever you save a JPEG by regular methods it needs to re-encoded, so after multiple re-saves the quality can become quite degraded. Lossless JPEG operations, on the other hand, work by rearranging the compressed data, without ever fully decoding the image, therefore there is no degration in quality.
Note, however, that lossless operations can only work on full DCT blocks, so when cutting/cropping the resulting image may contain at least a part of the area outside CutRect
depending on the need to align with to the nearest DCT block boundary (or multiple blocks, depending on the sampling factors).
| ||Demos\ImageEditing\LosslessCrop\LosslessCut.dpr |
// Rotate MyImage.jpg 90° clockwise
// Rotate MyImage.jpeg 90° clockwise
// Flip MyImage.jpeg horizontally