[neilep (OP)]

Dear Differenceologists,


see this image ?

 [ Invalid Attachment ]


Nice eh ?

It's only 7k !

Why does the bitmap version weigh in at a hefty 32k for something which looks exactly the same !!..same dimensions etc etc  ?


I want to know, I need to know
I do not know, ewe know !
Help me know , so that I can know
Answer me yes, and don't say no !


Quality poemage yet again !!


Neil
Image Enquirer


xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

[DoctorBeaver]

BMP images aren't compressed, JPGs are. It's the same with AVI and MPEG or WMV, and WAV and MP3.

[RD]

The jpeg and the bmp may look the same, but if you subtract one image from the other you will see where detail has been lost in the compressed jpeg (and jpeg artifacts).  If the images were identical subtracting one from the other should produce a blank black screen.

[DoctorBeaver]

RD - don't be wicked. Poor Sheepy has only just mastered painting by numbers. Now you're telling him about subtraction using images!  []

[RD]

I have exaggerated the contrast and brightness of the bmp-jpeg version

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[DoctorBeaver]

Show off  []

[BenV]

This is a very basic description, but should give you the idea...

A bitmap is a map of all the bits - in the file it says:

This pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
the next pixel is this colour
and so on...

A jpeg (which stands for Joint Photographic Experts Group - the people who developed it - just like Motion Pictures Expert Group MPEG video) instead says
The first 12 pixes are this colour
The next 20 pixels are this colour...

And so can save all the same info in a smaller file.

[rosalind dna]

What is a Bitmap in the difference to Jpeg and the other photographic or technical picture abbreviation that I have forgotten right now.

[DoctorBeaver]

If you want the best, scalable graphics format then you need vector graphics rather than raster graphics.

[paul.fr]

If you want the best, scalable graphics format then you need vector graphics rather than raster graphics.

 [O8)]
Wot you say man?

[paul.fr]

What is a Bitmap in the difference to Jpeg and the other photographic or technical picture abbreviation that I have forgotten right now.

Eh!

[DoctorBeaver]

If you want the best, scalable graphics format then you need vector graphics rather than raster graphics.

 [O8)]
Wot you say man?

I was REEFERing to the quality

[DoctorBeaver]

What is a Bitmap in the difference to Jpeg and the other photographic or technical picture abbreviation that I have forgotten right now.

Eh!

[paul.fr]

I was REEFERing to the quality

Wouldn't you have thought that the different developers would have got together on some sort of JOINT venture, to simplify things?

[DoctorBeaver]

I was REEFERing to the quality

Wouldn't you have thought that the different developers would have got together on some sort of JOINT venture, to simplify things?

Instead of just HASHing things together?

[rosalind dna]

I was REEFERing to the quality

Wouldn't you have thought that the different developers would have got together on some sort of JOINT venture, to simplify things?

Instead of just HASHing things together?

Dr Beaver thanks for the good explanation and I have a good digital Sony camera not a really technical one but it takes clear photos with Jpeg images. Like the ones of my cats that I posted.

[lyner]

JPEG is fine when you choose the appropriate quality for your desired display size. The problem with JPEG files is when you start to edit them. If you want to change the colour, gamma and sharpness (etc) the editor has, first, to change to a bitmap then change things then go back to JPEG. Some of the original 'artifacts' caused by the first JPEG coding get changed by the editing and, when re-JPEG'd, they can look worse than their original, acceptable level. Even just cropping the picture can mess things up.
RAW format is a compression system which avoids artifacts and makes image processing much safer. It takes a lot more memory, though, and means that your memory card cannot store anything like as many images. There are, unfortunately, a lot of different RAW formats and you need to translate them all into a suitable editable format (bitmap).
To see the effects of JPEG compression, look in the fine detail of your sharpest pictures and you will see spidery patterns all over - particularly when you use the highest compression. If you enlarge small portions of an original, they will show up on 'good' prints.

[Karen W.]

I have exaggerated the contrast and brightness of the bmp-jpeg version

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OH Shame on you RD...NOooooooo... How did you get Neily's Veronica into the general science forum... Oh Poor Neily.. Veronicas two timing you!!  LOL!

[RD]

In the UK in 1950s/1960s this view of Veronica was also a male hairstyle: a "Duck's Arse" or "D.A.", similar to a "Tony Curtis".
http://www.time.com/time/magazine/article/0,9171,867107-2,00.html