My pictures won't change file size when I change format

[Retribution]

I used to be able to change screenshots from games from bitmap to jpeg, and they would be a lot smaller in terms of megabytes/kilobytes. Now they aren't smaller. Why is this happening?

[Thor.]

Have you tried doing it manually through paint or photoshop, or "irfanview" :biggrin: great app, it has a option to decrease the size of a jpeg, massively, through its riot plugin.

[Retribution]

Well, usually for me just changing the file extension works, but now it doesn't.

[nosisab]

Well, usually for me just changing the file extension works, but now it doesn't.

What? it's the same as changing the extension to .zip and hope it will do the trick :)

 

BMP is raw, uncompressed format, the others are compacting formats and the differences are something similar to differences between zip, rar, 7z, arj, gz and so on... just for images instead general files (same rationales for sound).

[Thor.]

Why zip it, there is ways to compress a image. The way i do it works ok.

 

Its a great way of getting those 1080p images on the nexus. I could compress a 2mb file into such a small file size like around 160kb, of course there is a chance of quality loss.

[LHammonds]

Well, usually for me just changing the file extension works, but now it doesn't.

What? That should NEVER have actually worked. At best, your image viewer would try to open the JPG file and could tell it was actually a BMP file and display it correctly by loading the right library. No Windows operating system (by itself) has ever converted the actual type of a file by renaming the file extension. Renaming MYFILE.BMP to MYFILE.JPG would still result in the exact same file bit for bit and would not magically convert the image from a bitmap to a JPEG-encoded and compressed image. Want to see? Try it on any file and right-click on the file and open it with Notepad...the header information will remain the same no matter how you name the file.

 

To change an images file type, you HAVE TO use an image editor/converter to change the file itself. Which file type you convert to completely depends on the situation and there are several variables to consider.

 

File Size - Usually, the larger the file size, the less compression (if any) is used. The smaller the file size, usually means less image quality is retained.

 

Image Quality - Some types of files are structured to allow you to save over and over again without degrading the quality (last save is as good as the original image). Other file types and compressions can actually make the image look worse and worse each time you save it because the compressed image gets re-compressed again which resembles a fax-of-a-fax scenario.

 

File Type - Each file type has its own set of advantages and disadvantages but I'd be repeating myself If I said them again here so I'll just provide the link: Image Format Advantages and Disadvantages

 

Image Features - Certain file types support certain features. Need transparency? PNG will support it but not JPG. Need multiple layers? PSD will support it but not PNG. Need compression? JPG supports it but not BMP. etc.

 

Typically, when Oblivion screenshots are created in BMP format, you use something like Microsoft Paint to open the image and SaveAs to JPG format which changes the file format and apply JPEG compression to reduce file size. Here is an article that discusses this in detail: How To Convert Images

 

LHammonds