Image Compressing

**pavan** · May 1st, 2001, 06:10 AM

I'm working on a project which requires me store images from image control / picture box as a physical file. I've tried using SavePicture Command, but it stores only in BMP format which takes up a lot of space.

I would like to store it in a compressed format, so that the image occupies minimal amount of space say below 1KB.

Anybody who can help me out regarding this

**kedaman** · May 1st, 2001, 07:05 AM

what format would you like to compress it in, i happen to have source for jpeg compression

**pavan** · May 1st, 2001, 08:06 AM

Any type of format is OK for me even JPG as long as it offers the level of compression I need, ie., some where below 1KB

**kedaman** · May 1st, 2001, 08:18 AM

depends, compression level is defined as a ratio of the outcome data by the original. JPEG reduces the quality until a specified ratio is obtained

**pavan** · May 1st, 2001, 08:40 AM

can u send me the jpeg source u have

**kedaman** · May 1st, 2001, 08:44 AM

yeah i could if you give me your email ad

**pavan** · May 1st, 2001, 09:33 AM

my e-mail id : [email protected]

**kedaman** · May 1st, 2001, 10:19 AM

----- The following addresses had permanent fatal errors -----
<mailto:[email protected]>
(reason: 550 Invalid recipient: <"mailto:pavan_crm"@excite.com>)

**pavan** · May 1st, 2001, 11:18 PM

I could not get ur mail. Pls. mail me again

My email ID : Pavan ([email protected])

**vb_6_Programmer** · May 2nd, 2001, 12:45 AM

Lo Kedaman

can you also send me the source please

[email protected]

thank you

**kedaman** · May 2nd, 2001, 06:21 AM

n/p

**pavan** · May 2nd, 2001, 08:08 AM

sorry but I didnt catch ur meanining in N/P

**kedaman** · May 2nd, 2001, 08:14 AM

no problem.
btw, i'm had problem sending the mail, but now it succeeded, did you recieve it?

**pavan** · May 2nd, 2001, 08:46 AM

Thanx for ur reply. I think i got ur mail but i'm unable to view my inbox due to bad NET connection I'll try it again and let u know of it

**pavan** · May 3rd, 2001, 01:45 AM

Thanks Kedaman. I've got ur mail and have downloded it. I'm right now goin thru it and I find it very usefule.

Thanks again.

**pavan** · May 7th, 2001, 03:25 AM

Hi kedaman

I've gone thru ur code. Its compression capability is good. But I want to know how to restore the original image, after compressing it, with the same quality.

Thanx in Advance.

**PsychoMark** · May 7th, 2001, 03:43 AM

You can't, you need to use other graphics formats...

I've created my own with a little compression, you can find it here: http://psprogramming.virtualave.net/...7/dd/zlib.html

**Fleming** · May 7th, 2001, 07:37 AM

Hi kedaman,

Could you send me the code too.

[email protected]

Thanks in advance.

Sean.

**kedaman** · May 7th, 2001, 08:20 AM

Fleming: Sure.
pavan: A quality reducing format like jpeg looses quality every time you compress it, there's no way to restore it. Gif compression doesn't reduce the size as much as jpeg but keeps the quality, although with a max 256 color palette.

Dreamlax · May 9th, 2001, 05:19 AM

Hey Kedaman, can you send it to me (sorry I'm late) please?

[email protected]

BTW, the comma or fullstop in your signiture, is that your site? And howcome I'm not welcome? No, what I mean to have said is who is welcome?

**kedaman** · May 11th, 2001, 01:27 PM

ok sent, yeah it's my homepage, and youre welcome to the site, if you check it out

**pavan** · May 12th, 2001, 12:23 AM

Hi psychomark,

I've seen ur page and also downloaded the dlls. but the problem is they work only with BMPs whereas i need the compression utility for JPGs or GIFs which originally occupy a very little space.

**Fleming** · May 13th, 2001, 12:06 PM

Hi kedaman,

If you have already sent me the file, or even if you haven't, could you please resend it to:
[email protected]

another.com is way too slow, it takes ages for anything to get through.

Fleming.

**HarryW** · May 13th, 2001, 12:14 PM

PNG format is compressed, and it isn't lossy. Maybe you could find some source for that somewhere.

**PsychoMark** · May 13th, 2001, 02:21 PM

The reason I used BMP's for the compression, is that I can draw them using the raw byte data, whereas JPG's and GIF's would require you to unpack the file to disk first, then load it (using for example LoadPicture). If you don't mind temporary files, you can just compress and uncompress the pictures using the zLib.dll...

**pavan** · May 14th, 2001, 12:47 AM

Thanx Psychomark for giving me the advice I will try ur advice.

**pavan** · May 14th, 2001, 11:26 PM

Hi PsychoMark,

I've tried compressing and decompressing of JPGs with zlib.dll as u suggested.

But while compressing the compresion ratio seems to be very little / negligble for JPGs. the compressed file was only a few bytes smaller than the original file.

And while decompressing it, I repeatedly got an error saying 'out of stack space'.

can u help me out of it.

Thanx in Advance

**PsychoMark** · May 15th, 2001, 02:17 AM

1. The low compression ratios are not that strange, since JPG's are already compressed. For example, use WinZip to compress a Bitmap and a JPG in the same way, you'll notice that the JPG isn't compressed as much as the BMP.

2. Can't do anything without code, so if you still want to compress JPGs, send the code which you used to compress it, and mark the line where the error occurs...

**pavan** · May 15th, 2001, 06:11 AM

Hi Psychomark,

I haven't changed much the code i've downloaded. I'm getting any error at clsBitmap.cls file. Anyway I'm sending it to u as attached Zipped file

**PsychoMark** · May 15th, 2001, 06:20 AM

Code:

    ' Create a bitmap out of the Byte array
    cBitmap.ReadFromByteArray bData()

This is not possible, since we're reading JPG's. Comment the line out, and do the same for these:

Code:

    cBitmap.ResizePicturebox picImage
    cBitmap.BlitToDC picImage.hDC
    picImage.Refresh

Haven't tested it, but it should work. The errors are occuring because you're trying to read the bitmap format from a JPG, which could cause VB to crash...

**pavan** · May 22nd, 2001, 12:23 AM

Hi,

I've tried all the advices given to me but the compressed file size seems to be a min. of 1.3KB max. its not going down further. i require the compressed image to be less than 1 KB. I've also tried reading the image pixel by pixel and storing it in the file with all the common colors codified ( an idea from vbsquare.com) but even then it has come to 1.2KB. so if anybody out ther can tell me how to achieve this i'll be thankful

Thnx in advance

**PsychoMark** · May 22nd, 2001, 01:15 AM

Can you give me the image you want to compress? If so, I can check some other possibilities...

**pavan** · May 22nd, 2001, 03:09 AM

Hi PsychoMark

The image i want to compress is not specific. It ithe photograph of a person. U can take any photograph of a person and then try out the possibilities.

**PsychoMark** · May 22nd, 2001, 03:15 AM

Ic, well, let me know the average dimensions then, since the file size can vary a lot depending on the dimensions...

**pavan** · May 23rd, 2001, 05:57 AM

Hi

I've a requirement of Image dimensions are as follows.

The dimensions for one image are 19.05 x 25.4 mm / 0.75 x 1.0 inch

the dimensions for the other are 25.4 x 6.35 mm / 1.0 x 0.25 inch

all the dimensions are Width x Height

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