Help with JPG to BMP conversion - Please

[Pete Simmons]

OK here is the picture.

On the right the picture in jpeg greyscale

save it as bmp it still looks OK on the screen but close it and when you reopen it you get the picture on the left.

It is NOT Photoshop. I have tried this in Corel Paint and Paint, and get the same results. Up until yesterday I have been doing this often for import to Photograv and it has worked fine. Yesterday this stuff starts.

Any ideas??? Maybe a windows auto update got to me not sure.

Help.

[John Hart]

Hmmm...What I did was take the jpeg and increase the resolution to 300 dpi and the image width to 1200, then I saved it as a bmp. This created a 5M file. When I brought it back, it was very large compared to the original jpeg so I resized it to 25% and stuck it beside the original. This is what I got. I did use Photoshop though.
The bitmap is on the left

[Pete Simmons]

Original photo was 300 dpi.

The picture shown is a screen grab of the 2 pictures side by side in Photoshop. I expect the resolution to be low.



John can I send you the photo?

Pete

[John Hart]

Sure Pete...I'll give it a whirl. my email is johnhart@handykraft.com

[Bill Stein]

Pete,

I see a dither problem. The photo on the right appears to be halftone. The photo on the left looks like diffusion dithering. I am stumped as to why you get the same results regardless of the program used because, as far as I know, the dithering settings are set inside of Photoshop, Corel, etc.

The only thing that I can suggest is that you look up "dithering" in your program's help file. The information there may lead you to solving the problem.

Bill

[Lee DeRaud]

OK here is the picture.

On the right the picture in jpeg greyscale

save it as bmp it still looks OK on the screen but close it and when you reopen it you get the picture on the left.

It looks like it got saved as a monochrome (1-bit) BMP instead of a grayscale (8-bit) BMP, but I have no idea what would make it do that way globally (ie. across multiple applications).

[Pete Simmons]

When I reopen the bmp in Photoshop it looks bad. It is also in indexed color. I switch to greyscale and it asks if I want to discard color info. I do and it looks great.

Save as bmp again and I am right back to the bad picture and in a circle I cannot seem to get out of.

When and did it on another computer I have and got the same results.

[John Hart]

I spent some time today at work on it. I think I got a pretty good result. I'll send it as soon as I get home...see whatcha think

[Pete Simmons]

John:

I bet the bmp you have and will send me is great. I am worried that as soon as I open it I will be right back to the poor quality picture. Did you see in one of my posts, ( Should have not started another thread ) that when I open the bad looking bmp it is in indexed color. I change it to greyscale it asks if I want to discard color info, I do and it looks great. Save it as a bmp and I am right back where I started - Poor quality bmp.

Very strange.


Thanks for your help.

[Pete Simmons]

John thanks for all the help but my concerns were right. I got the file.

I look at it with windows viewer it looks fine.

I open it in Photoshop or Photograv it looks bad.
In Photoshop it comes in as indexed color.

I change it to grayscale and discard color info and it looks great.

Save it as bmp and I am right back in the bad circle again.

Enough for today. Will work on the problem again tomorrow.

[John Hart]

Ok...I looked at what Bill Stein was saying about dither and made that adjustment. I was able to save it as 8-bit grayscale and bring it back in and it looked good. It still comes in as indexed color but it's not grainy and the conversion to grayscale shows no difference. I'll email this one and see whatcha think.

[Robert Stremcha]

Grayscale images opened in Photoshop always come in as indexed color, no matter how many times you saved them as grayscale.

[Bill Stein]

Pete,

How are you doing the conversion to bmp? If you do it inside Photoshop, it will dither the photo and give you the result I see on your left hand photo. If you do a Save As and select bmp in the Format box, it will save it as a grayscale photo and it will look like your right hand photo.

Bill