<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-8E794D5A-9C83-54EB-AD5A-6A74BB155223" xml:lang="en"><title>JPEG

Image Transform Extension Guide</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This document introduces you to the JPEG image transform extensions. </p>

<section id="GUID-3333CA2A-EF84-5E7B-B9BE-8FF00523897F-GENID-1-8-1-18-1-1-5-1-6-1-12-1-4-1-3-1-3-1-3-1-2-2"><title>Purpose</title> <p>The

Image Transform framework supports standard extensions for advanced JPEG functions. </p> <p>The

functions are, </p> <ul>

<li id="GUID-5AEE7F00-B5AE-5D17-8280-BB86E1C3F309"><p><xref href="GUID-8E794D5A-9C83-54EB-AD5A-6A74BB155223.dita#GUID-8E794D5A-9C83-54EB-AD5A-6A74BB155223/GUID-3F1A77BC-C5C3-5A3D-B823-7310B97D449A">Orientation</xref> (Rotation and Mirror over horizontal and vertical Axis) </p> </li>

<li id="GUID-48438448-064A-5FE4-96D4-769336CFC50E"><p><xref href="GUID-8E794D5A-9C83-54EB-AD5A-6A74BB155223.dita#GUID-8E794D5A-9C83-54EB-AD5A-6A74BB155223/GUID-3132C68A-4A30-51FD-9259-9425E3E5B5AE">Overlay</xref>  </p> </li>

<li id="GUID-03E14C2D-A7D9-532F-9E3A-BB8A38770929"><p><xref href="GUID-8E794D5A-9C83-54EB-AD5A-6A74BB155223.dita#GUID-8E794D5A-9C83-54EB-AD5A-6A74BB155223/GUID-AAD925E2-9450-5ADC-B2D2-FF106392FC4C"> Squeeze</xref>  </p> </li>

</ul> </section>

<section id="GUID-3F1A77BC-C5C3-5A3D-B823-7310B97D449A"><title>Orientation</title> <p>The

COrientationTransformExtension extension to CImageTransform allows you to

rotate in steps of 90 degrees or to mirror a JPEG file either from file or

memory. </p> <p>When you require an Image Transform plugin which supports

the Orientation extension, call <xref href="GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4.dita#GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4/GUID-141A948E-6070-335D-B0B2-1F4AD283EC1A"><apiname>CImageTransform::SetTransformationsL()</apiname></xref> or <xref href="GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4.dita#GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4/GUID-429C3968-9EB4-3B6E-85FF-13244E4505D2"><apiname>CImageTransform::EOrientation()</apiname></xref>.

The client must get the COrientationTransformExtension extension and use this

to set up the required transformation: </p> <codeblock id="GUID-12531AE6-3383-50F3-8D89-629010D967E1" xml:space="preserve">

IMPORT_C  void COrientationTransformExtension::SetOrientationL(TOrientation aOrientation);

</codeblock> <p>The orientation changes supported by the <xref href="GUID-593AD11D-3CE7-39E7-B5FE-EDEDABE8D936.dita"><apiname>COrientationTransformExtension</apiname></xref> are, </p> <ul>

<li id="GUID-E3056EBA-DC74-5D99-95D5-3016AEAADA4A"><p>90 degree clockwise </p> </li>

<li id="GUID-9E607A83-0846-56FC-95D4-CD7250934EC0"><p>180 degree clockwise </p> </li>

<li id="GUID-27A48EA1-7774-5DA8-9FCB-201965A9EA59"><p>270 degree clockwise </p> </li>

<li id="GUID-53B7C705-D2EE-5729-BE74-91291D7F30C5"><p>mirroring over the vertical

axis </p> </li>

<li id="GUID-D7806048-D30A-5D77-BA5E-1F581E76D5CC"><p>mirroring over the horizontal

axis </p> </li>

<li id="GUID-88EDAE03-DB13-5BF9-BAE8-60C20065D114"><p>transpose over the main

diagonal </p> </li>

<li id="GUID-8E508BFF-714C-58B4-A0BB-82B6507FC7EA"><p>transpose over the minor

diagonal. </p> </li>

</ul> <p>In the example function below a JPEG image is rotated by 90 degrees: </p> <codeblock id="GUID-9C13D4D9-1772-5FC1-A294-F0B52A5EFFA2" xml:space="preserve">

    // Create the image transform

       CImageTransform* imageTransform = CImageTransform::NewL(iFs);

       CleanupStack::PushL(imageTransform);

    // Setup the image transform

       imageTransform->SetSourceFilenameL(aSrcFileName);

       imageTransform->SetDestFilenameL(aDestFileName);

       imageTransform->SetTransformationsL(CImageTransform::EOrientation);

       imageTransform->SetupL();

    // Get the extension plugin supporting orientation

       TUid lRotateUid = {KUidOrientationTransformExtension    };

       TInt err = KErrNone;

    COrientationTransformExtension* lRotateExt = static_cast<COrientationTransformExtension*>

    (imageTransform->Extension(lRotateUid, err));

 // Check here whether the plugin supports this extension or not set the orientation on 

 // the plugin    

 lRotateExt->SetOrientationL(COrientationTransformExtension::ERotation90DegreesClockwise);

    // Perform the transformation

      imageTransform->Transform(aStatus);

    // CImageTransform::Transform() is an asynchronous function

    // and the result of the transformation would be known in the

    // RunL() function of the active object associated with the aStatus

</codeblock> <p>The image rotation can be performed in the compressed domain

allowing a transformation of the image. Benefits of speed and memory usage

can be obtained dependent on the implementation of the plugin. </p> </section>

<section id="GUID-3132C68A-4A30-51FD-9259-9425E3E5B5AE"><title>Overlay</title> <p> <xref href="GUID-83EA2789-C3FE-383A-B81F-E9E362FE4283.dita"><apiname>COverlayTransformExtension</apiname></xref> extension

to Image Transform framework allows lossless overlay or blend of images. Examples

of the use of <xref href="GUID-83EA2789-C3FE-383A-B81F-E9E362FE4283.dita"><apiname>COverlayTransformExtension</apiname></xref> include adding

timestamp or place-stamp, some text or inserting a company logo. The images

below show an example of overlay functionality: </p> <fig id="GUID-BA901C57-D744-5353-8B25-2195EA084016">

<image href="GUID-E09CA978-2599-50F9-AF6D-077AD7D5CA6F_d0e309541_href.jpg" placement="inline"/>

</fig> <p>The image overlay transformation can, depending on its implementation,

be very fast eliminating the need to decode the whole image making it very

useful, for example a camera application. The types of image that can be overlaid

onto the main JPEG image can be discovered through the extension. It is also

possible to overlay a <codeph>CFbsBitmap</codeph>. If you need transparency,

then you have to choose an image format supporting a transparency channel

such as PNG. </p> <p>When you require an Image Transform plugin which supports

the Overlay extension, call <xref href="GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4.dita#GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4/GUID-141A948E-6070-335D-B0B2-1F4AD283EC1A"><apiname>CImageTransform::SetTransformationsL()</apiname></xref> or <xref href="GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4.dita#GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4/GUID-198CAB14-A6CB-3D51-9404-C4DED1DCF215"><apiname>CImageTransform::EOverlay()</apiname></xref>.

The client must get the COverlayTransformExtension extension and use this

to set up the required transformation. The client can control the desired

position for overlay, and the transparency for image. The example below show

the successful setup for <xref href="GUID-83EA2789-C3FE-383A-B81F-E9E362FE4283.dita"><apiname>COverlayTransformExtension</apiname></xref> with

the JPEG image overlaid by an image at (0,0) position co-ordinates: </p> <codeblock id="GUID-648E2DC3-9BA2-59D3-88DA-3E9C31BC3F18" xml:space="preserve">

    // Create the image transform

    CImageTransform* imageTransform = CImageTransform::NewL(iFs);

    CleanupStack::PushL(imageTransform);

    // Setup the image transform

    imageTransform->SetSourceFilenameL(aSrcFileName);

    imageTransform->SetDestFilenameL(aDestFileName);

    imageTransform->SetTransformationsL(CImageTransform::EOverlay);

    imageTransform->SetupL();

    // Get the extension plugin supporting overlay

    TUid lOverlayUid = {KUidOverlayTransformExtension    };

    TInt err = KErrNone;

    COverlayTransformExtension * lOverlayExt = static_cast< COverlayTransformExtension *>

 (imageTransform->Extension(lOverlayUid, err));

    // Check here whether the plugin supports this extension or not Set the position on 

 //  the plugin

    lOverlayExt->Position(TPoint(0,0));

    // Set the overlay file and its type

    lOverlayExt->SetOverlayFileL(aOverlayFileName, KImageTypeJPGUid);

    // Perform the transformation

    imageTransform->Transform(aStatus);

    // CImageTransform::Transform() is an asynchronous function

    // and the result of the transformation would be known in the

    // RunL() function of the active object associated with the aStatus

</codeblock> </section>

<section id="GUID-AAD925E2-9450-5ADC-B2D2-FF106392FC4C"><title>Squeeze</title> <p>The <xref href="GUID-1B022316-410D-328C-AFB2-E3A339E1609B.dita"><apiname>CSqueezeTransformExtension()</apiname></xref> extension

to the Image Transform framework allows, </p> <ul>

<li id="GUID-485ED69C-7895-5B8F-B2DC-D8A165F74D59"><p>Auto-resize </p> </li>

<li id="GUID-8DDD9BE0-F079-5F6F-B4D7-26DC45170BEC"><p>Squeeze. </p> </li>

</ul> <p>A auto-resize adjusts the image size and encoding quality to achieve

a desired file size. If the file size requirement has not been met, then you

can use squeeze to compress the image even further. The JPEG squeeze module

is a convenient tool when creating MMS. </p> <p>When you require an Image

Transform plugin which supports the Squeeze extension, call <xref href="GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4.dita#GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4/GUID-141A948E-6070-335D-B0B2-1F4AD283EC1A"><apiname>CImageTransform::SetTransformationsL()</apiname></xref> or <xref href="GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4.dita#GUID-37B0C02C-F518-3ADD-8828-90FD6B3E9DE4/GUID-FC837A02-243D-3A5B-A81D-63802678F6C6"><apiname>CImageTransform::ESqueeze()</apiname></xref>. </p> <p>Squeezing an image can be accomplished through: </p> <codeblock id="GUID-12A6E7C4-8627-5ACC-8692-64F247FB518D" xml:space="preserve">

IMPORT_C void CSqueezeTransformExtension::SetDestSizeInBytes(TUint aMaxDestDataSize ) ;

</codeblock> <p>Or </p> <codeblock id="GUID-97A7CE4F-A227-51EE-B8E6-CC04C5A2491A" xml:space="preserve">

    IMPORT_C void SetAdvancedSqueezeModeL(TAdvancedSqueezeParams* aSqueezeAutoResizeParams ) ;

</codeblock> <p>In the latter case can be made through the use of <xref href="GUID-4372B86B-111B-3B9E-838A-511D247846D4.dita#GUID-4372B86B-111B-3B9E-838A-511D247846D4/GUID-15AB4D19-1FDE-3D29-AED2-7776E3E08C10"><apiname>TAdvancedSqueezeParams::TAutoResizeAction</apiname></xref>.

The enumeration to do auto resize are, </p> <ul>

<li id="GUID-3240A4EE-6904-536C-BA05-5995738CE048"><p> <xref href="GUID-DAEB147E-2A50-30F5-85C8-863DC8C21AF7.dita"><apiname>         

       EAutoResizeActionPreserveSourceEncodingQuality</apiname></xref> for preserving

the source encoding quality while shrinking the width and height of the image </p> </li>

<li id="GUID-B29AE145-B946-59CD-879E-6F77F0E48563"><p> <xref href="GUID-EAF60EAB-3E65-34AE-BD3F-C32BA331BCEE.dita"><apiname> EAutoResizeActionPrioritizeLargeImageSize</apiname></xref> for

preserving the maxImageSize while lowering the encoding quality </p> </li>

<li id="GUID-2B98FA22-2853-5DB0-B9A2-7B2BC6080522"><p> <xref href="GUID-EAF42079-109B-36E7-940F-C10C10743E31.dita"><apiname>EAutoResizeActionResizePrioritizeHighEncodingQuality</apiname></xref> for

preserving the highest possible encoding quality while shrinking the width

and height of the image </p> </li>

<li id="GUID-3848F63C-D0CF-5888-BC68-127AA29DFE81"><p> <xref href="GUID-D8807BBD-5EAE-3BBE-B408-5841D7554287.dita"><apiname>EAutoResizeActionMiddleCourse</apiname></xref> for

simultaneously lower the encoding quality and shrink the width and height

of the image. </p> </li>

</ul> <p>These settings are used by the auto resize to determine size and

encoding quality for the new image file. </p> <p>The JPEG squeeze enblaes

images to be set to a enblaes pre-defined size. This is useful if storage

size is critical or if there are limitations when sending images i.e. MMS

file size. The dimensions of the image are preserved; the JPEG compression

ratio being changed to maintain the image size. </p> <p> <b>Note:</b> The

JPEG squeeze functionality must be used with care. Drastically decreasing

file size will result in poor image quality. </p> <p>In the below example,

the JPEG image is squeezed to get a file size less than the specified maxium

size: </p> <codeblock id="GUID-9E529BC6-0042-5EBE-A5AE-8F2ADAA8E4D8" xml:space="preserve">

    // Create the image transform

    CImageTransform* imageTransform = CImageTransform::NewL(iFs);

    CleanupStack::PushL(imageTransform);

    // Setup the image transform

    imageTransform->SetSourceFilenameL(aSrcFileName);

    imageTransform->SetDestFilenameL(aDestFileName);

    imageTransform->SetTransformationsL(CImageTransform::ESqueeze);

    imageTransform->SetupL();

    // Get the extension plugin supporting squeeze

    TUid lSqueezeUid = {KUidSqueezeTransformExtension    };

    TInt err = KErrNone;

    CSqueezeTransformExtension * lSqueezeExt = static_cast< CSqueezeTransformExtension*>

(imageTransform->Extension(lSqueezeUid, err));

    // Check here whether the plugin supports this extension or not

    // Set the max dest size in bytes    

    lSqueezeExt-> SetDestSizeInBytes(aMaxSizeInBytes);

    // Perform the transformation

    imageTransform->Transform(aStatus);

    // CImageTransform::Transform() is an asynchronous function

    // and the result of the transformation would be known in the

    // RunL() function of the active object associated with the aStatus

</codeblock> <p>The example code below show how the JPEG squeeze image is

used to make an image fulfill the MMS ‘Image Rich’ class constraints, i.e.

file size less than 100k bytes and image size no more than 640*480 pixels. </p> <codeblock id="GUID-C04CB828-3307-5079-91CD-BEA7A15F0215" xml:space="preserve">

    // Create the image transform

    CImageTransform* imageTransform = CImageTransform::NewL(iFs);

    CleanupStack::PushL(imageTransform);

    // Setup the image transform

    imageTransform->SetSourceFilenameL(aSrcFileName);

    imageTransform->SetDestFilenameL(aDestFileName);

    imageTransform->SetTransformationsL(CImageTransform::ESqueeze);

    imageTransform->SetupL();

    // Get the extension plugin supporting squeeze

    TUid lSqueezeUid = {KUidSqueezeTransformExtension    };

    TInt err = KErrNone;

    CSqueezeTransformExtension * lSqueezeExt = static_cast< CSqueezeTransformExtension*>

(imageTransform->Extension(lSqueezeUid, err));

    TInt res = KErrNone;

    TInt newSize = 0;

    TAdvancedSqueezeParams info ;

    // MMS Image Rich

    info.iMaxDestSizeInBytes = 100000;

    info.iMaxImageSize.iWidth = 640;

    info.iMaxImageSize.iHeight = 480;

    info.iMinImageSize. iWidth = 160;

    info.iMinImageSize. iHeight = 120;

    info.iResizeAction = EAutoResizeActionPrioritizeLargeImageSize;

    info.iMinEncodingQuality = 0.5f;

    info.iSamplingUid = KUidSamplingColor420;

    lSqueezeExt->SetAdvancedSqueezeModeL(&info);

    // Perform the transformation

    imageTransform->Transform(aStatus);

    // CImageTransform::Transform() is an asynchronous function

    // and the result of the transformation would be known in the

    // RunL() function of the active object associated with the aStatus

</codeblock> </section>

</conbody></concept>