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Date Posted: 16:29:51 06/04/01 Mon
Author: Ann Weaver
Subject: Re: How save BW image as JPEG?
In reply to: Michel 's message, "Re: How save BW image as JPEG?" on 17:41:49 05/31/01 Thu

I have this all working now but is running fairly slow due to the conversion from B/W to Grayscale. I am scanning the images at B/W 300dpi which seems to be about the minimum I can go and still get a good read of the barcode contained in the image. However, due to the size of the image it makes the conversion from B/W to grayscale take about 10 seconds or so to convert (which is a necessity to store the image as .jpg). I then resize the image as I don't need/want to store an image of that size. If I resize the image prior to the conversion it goes faster but I lost a lot of image quality that way. Conversion first, then resize works great but lacking speed.

Does anyone have any suggestions on how to speed up this process?


>Hi Ann,
>The TJpegGraphic will allow saving images that have an
>image format of ifTrueColor or ifGray256.
>I would first convert you image to ifGray256, using
>the TImageFormatTransform class. There is an example
>of this in the DemoForm.Pas unit,
>FormatConversionMenuClick event handler. Then you will
>be able to save it as a JPG.
>Saving BW images in JPG is generally not a good idea
>though. JPG is optimized to compress color images, and
>slightly degrades the quality. For BW images, you
>would get better compression with Tiff group IV
>compression, and there is no quality loss.
>Best regards,
>>I have an application that acquires images from a
>>scanner in Black & White and then detects a barcode in
>>the image. I then want to save the image to disk as a
>>.jpg with a filename of the barcode result.
>>I have to scan the image as BW for the barcode
>>detection to work.
>>Everything is working great with the exception that I
>>cannot save a BW image to a .jpg. I can save to a
>>Bitmap but I need .jpg. How can I convert the image
>>so it can be saved as a .jpg?
>>I am a registered user of the Envision library and am
>>using the Pegasus SmartScan Xpress software to detect
>>the barcode in the image.
>>Can anyone provide any assistance?

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