How to use
- Open the same bitmap.
- Try quality 80 and quality 60.
- Read the size line before you delete the BMP.
Formula / how it works
The same 32 by 16 bitmap becomes a JPEG. The grid stays 32 by 16. JPEG has no alpha, and this bitmap had none, so nothing is painted white that was not already a colour. Quality 80 and quality 60 are both runs. On two flat colours the file size may not move. A photograph stored as BMP will move, and the size line is the number to trust. The bitmap is uncompressed on disk. The JPEG is the smaller shareable file. Detail is not added. A blurry bitmap stays blurry. Use BMP to PNG when you want a lossless container instead.
Quality 80 and quality 60 on two flat colours are a poor lesson in file size. Use them to see that the grid stays 32 by 16. Use a photographic BMP when you want the size line to move. The JPEG will not grow an alpha channel. The bitmap you opened remains on disk.
Quality 80 and quality 60 are two encodes of the same 32 by 16 bitmap. Flat red and blue hide the savings a photographic bitmap would show. Read the size line on that photograph before you throw the BMP away. The JPEG cannot hold a transparent pixel. These bars did not have one. The page stays in the browser. A blurry bitmap is still blurry after the encode, because nothing is sharpened. PNG remains the lossless choice when the next tool can read it.
Do not delete the bitmap until a photograph, not these bars, has shown a size you like at 80 or at 60. The bars only prove 32 by 16. They are a bad teacher of savings. The JPEG has no alpha. The page is local.
Treat quality 60 as a question you ask a photograph, not a question these bars can answer. The bars answer a different question: the JPEG is still 32 by 16. Flat colour hides savings. A scan stored as BMP will not hide them. There is no alpha to keep. There is no sharpening. The bitmap remains on disk until you delete it yourself.
Run quality 80 and quality 60 on a photographic bitmap before you trust the bars. The bars are 32 by 16 at both settings and that is all they prove. A scan will show the savings the bars hide. The JPEG will not grow transparency and will not sharpen mud. Delete the BMP only after that photograph looks right. Until then both files can sit in the same folder. The bars remain the grid check at 32 by 16, and a photographic bitmap is the only file that should decide the quality. Leave both files in the folder until that photograph has been judged at the quality you actually want.
A lossless container is BMP to PNG.
Worked examples
Bitmap bars at quality 80
Inputs: b2j-f: bars-32x16.bmp | b2j-q: 80
On this page, take bars-32x16.bmp, then 80 and press Convert. Flat colours may not shrink when quality drops.
Result: BMP to JPEG: 32×16. If a pixel was transparent, it is now white. 0.8 KB
Bitmap bars at quality 60
Inputs: b2j-f: bars-32x16.bmp | b2j-q: 60
On this page, take bars-32x16.bmp, then 60 and press Convert. Flat colours may not shrink when quality drops.
Result: BMP to JPEG: 32×16. If a pixel was transparent, it is now white. 0.8 KB
Use cases
- Making a shareable JPEG from an uncompressed scan.
- Keeping 32 by 16.
- Accepting that flat colours may not shrink further.
- Leaving alpha out, because JPEG has none.
Tips & limitations
- A photo BMP will move more than these bars.
- Quality is the JPEG slider.
- The grid stays put.
- PNG is the lossless alternative.
FAQ
What size is the JPEG?
32 by 16.
Did the bars gain a white hole?
No. They were opaque, and JPEG cannot store a hole anyway.
Will quality 60 always be smaller?
Not on two flat colours. Read the line.
Is detail restored?
No.
Is the bitmap uploaded?
No.
Which page keeps it lossless?
BMP to PNG.
The bars bitmap is a weak test of JPEG savings. A photograph stored as BMP is the file that shrinks.