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From Kevin Theisen <ke...@tfam.us>
Subject Fwd: Sanselan Issue
Date Sun, 03 Aug 2008 20:37:04 GMT
Hi Charles,

Thanks for the quick response. I opened up a ticket. I don't know how  
to attach images to the issue, so I provided a URL to the one in  
question.

Yes, the image goes to near black in about 3-4 cycles.

Thanks again,
Kevin Theisen

Begin forwarded message:

> From: "Charles Matthew Chen"
> Date: August 3, 2008 1:17:25 PM PDT
> To: "Kevin Theisen"
> Subject: Re: Sanselan Issue
>
> Hi there Kevin,
>
>   How are you?  There's a few possible reasons for this.
>
>   Can you please open a ticket around this on JIRA (sanselan's issue
> tracking system?
>
> https://issues.apache.org/jira/browse/SANSELAN
>
>   Please attach the original source image (not that transition image
> you attached to this email).
>
>   Also, let's move this conversation to sanselan-dev, the project's
> mailing list.
>
>   One possible explanations come to mind: for grayscale images,
> Sanselan's default behavior is to create a BufferedImage of type
> TYPE_BYTE_GRAY.  TYPE_BYTE_GRAY images have the unfortunate behavior
> of slightly altering values.  ie.:
> """
> value1 = image.getRGB(x,y);
> image.setRGB(x,y, value1);
> value2 = image.getRGB(x,y);
> // value1 != value2
> // this code is from memory, I may have capitalization or param  
> order reversed.
> """
> Just this week, I was considering how to best work around this.  I'm
> not sure this explanation addresses the problem you are seeing if that
> png went to near-black in just 3 read-write cycles.  The problem
> around TYPE_BYTE_GRAY is akin to a rounding error and isn't likely to
> shift a value more than 3 shades of gray.
>
>   Is that PNGDarker.png that you attached indicative of how quickly
> the image darkens, ie. it goes to near black in just 3 cycles?
>
> Charles.
>
>
> On Sun, Aug 3, 2008 at 8:41 PM, Kevin Theisen wrote:
>> Hello Charles,
>> I have a quick questions about your great package. I am currently  
>> using the
>> latest 0.94 version.
>> When saving and loading pngs with Sanselan, black and white images  
>> get
>> darker with each save and load (view attached image). All images  
>> are held in
>> memory as BufferedImages (ARGB). Have you ever seen this weird  
>> behavior
>> before or how I may fix it?
>>
>> Thank you so much,
>> Kevin Theisen
>> kevin@ichemlabs.com
>


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