Heya Gogi --

I use DXTBmp to save all of my aircrafts (AI as well as flyable aircraft) textures into DXT1 format with NO Mipmaps.  You can get DXTBmp here for free:

[url]http://www.mnwright.btinternet.co.uk/[/url]

Just click on the left where it says "Program List" and you'll find DXTBmp about halfway down.

First off Gogi make a temporary backup of the Aircraft's Texture folder.  If you are running Windows XP use the Windows Explorer to Open the aircraft folder.  Right-click on the Texture folder and left-click "Copy".  Move your mouse pointer to any "free" area on your screen that does not show an icon.  Right-click again and left-click "Paste".  You will see a new folder named "Copy of Texture".  What this does is make a backup of your Texture folder.  That way if you make a mistake with the next steps in the process you have backups handy that you can Copy/Paste back into your original Texture folder.  When you are satisfied with your finished project you can delete this "Copy of Texture" folder.

Next run the DXTBmp program.  Up at the top of the program you will see a menu bar.  Click on "Prefs" and uncheck the "Include MIPs" entry.

Next click on "File" then "Load Extended Image".  An Open Screen will appear.  Select the aircraft that you wish to adjust the texture of.  Most of the time I just adjust the fuselage, tail, wings, and vertical stabilizer.
You should see different files named xxx.bmp in the aircraft's Texture folder.  Look for files that are named to resemble the words fuselage, tail, wings, or vertical stabilizer.  Note that each file should have an underscore "_" and either the letter "T" or the letter "L" (uppercase or lowercase -- it doesn't matter) in it.
The "T" letter designates that the texture is used during the daytime.  The letter "L" designates that the texture is used during the night or low light conditions.
Don't worry about the textures with the "L" designation.  You will not need to modify them, only the ones with the "T" letter in the title of the bitmap.

Highlight each one with the "_T" singly.  Let's say that the Texture Folder of the aircraft has a file named "fuse560_T.bmp".  By the explanation above you know that "fuse" is short for "fuselage".  The "560" doesn't really matter.  The "_T" means that it is a daytime texture.  In the Open Window of the DXTBmp program double click this "fuse560_T.bmp" file.  The program will display a color drawing of this bitmap.  Look at this color drawing.  If it seems to be sharp and clear then you don't need to modify it further.  Merely click on the DXTBmp "File" menu item at the top and then click "Save Extended Image".  A Save window will appear.  

It is very important to check the two entry fields labeled "File Name" and "Save as Type" near the bottom of the Save Window.

"File Name" Blank:
Save this image using the [b]exact[/b] same file name as before (example: fuse560_T.bmp).  

"Save as Type":
Don't change this!  Normally you should keep the Texture File Type the same as the original.

Click OK at the bottom of the Save screen.  When you click OK a prompt screen will appear saying "this file already exists -- do you want to replace it"?  Click "Yes"

What this does, Gogi is to remove the MIPmaps from the texture image.  On some graphics cards the MIPmaps can make the aircraft look "blurry" while in FS 2004 Spot View.  Removing the MIPmaps from the texture will make the aircraft look a lot more clear.

Go to the DXTBmp program and again click on "File" then "Load Extended Image".  When the Open screen appears select the next texture.  Let's say that the Texture Folder of the aircraft has a file named "737wing_T.bmp".  By the explanation above you know that "wing" shows this as a wing texture and the "_T" means that it is a daytime texture.  

Repeat the steps above on only the textures with the "_T" designation until you remove the MIPmaps on the aircraft's fuselage, tail, wings, and vertical stabilizer.

That's it!  Startup the FS 2004 program and select the aircraft and see what it looks like in Spot View during the daytime.  You should see a big difference in the clarity.

I also use DXTBmp in addition to Paint Shop Pro in order to repaint aircraft that I fly.  It's a challenge to get the textures "just right".  

Hopefully this will resolve your issue.  If not, you may wish to use Paint Shop Pro or Adobe Photoshop to "Clear-Up" your textures.