Impro Aerospace is a full-service precision casting and precision machining component manufacturer. Over the past decade, Impro Aerospace has been supplying high quality products to renowned global OEM customers in the aerospace, medical and energy markets.

Castings are poured via investment casting, permanent mold casting, and shell mold casting processes from a few ounces up to 100 pounds. Materials include aluminum, super alloy, stainless steel, and low alloy steel. Custom ultra-precision 5-axis and 4-axis CNC milling services are available for precision machining parts out of bar stock, plates, and billets, whether for high, medium, or low volumes.

Being ISO 9001, AS9100 and ISO 13485 certified, we ensure manufacturing processes and our products conform to the highest quality standards. In-house NADCAP certified special processes and Lab/NDT testing not only ensure high quality but also reduce product lead time.

Immigration Forms Software, Immigration Software, Immigration Forms, law firm software, immigration practice software, management software, immigration case software, immigration management. Impro is a global leading manufacturer of high-precision, high-complexity and mission-critical casting and machined components for diverse end-markets. We supply customized casting and machined products and provide surface treatment services to a well-diversified global customer base.

Impro’s in-house tooling design/manufacturing capabilities and rapid prototype facilities are highly valued by customers who seek quick turnaround on new product development, robust process control, and expedient delivery.

Our goal is to become one of the top players for supplying medium to high complexity castings and precision machining products to the aerospace, energy and medical industries. We will continue to expand our customer base and deepen relationships with leading global OEMs whose equipment and systems demand high quality and mission-critical components as well as global services for engineering support and supply chain management.

Investment Casting

robust process capabilities

Permanent Mold Casting

Low-Pressure Permanent Mold

gravity and rotary pouring

We primarily manufacture castings for aerospace, energy and medical application via the investment casting process. In addition, we offer permanent mold, low-pressure permanent mold, and shell mold casting processes to meet the all-around needs of our customers to provide a total solution. The typical aerospace casting requires robust process capabilities to ensure consistency of product quality and ability to hold extremely tight tolerances….Read More

Impro Gun

Permanent mold casting is a metal casting process that uses reusable molds (“permanent molds”) usually made from metal. Our process uses gravity and rotary pouring. At Impro, we cast aluminum using the permanent mold casting process with casting sizes up to 16 inches in diameter or length and weighing up to 35 pounds. Typical products that we produce using this process include gear housings, pipe fittings, adapter ports, fuel injection housings, pump housing, front housing, pump covers, and flange mounting…. Read More

Shell mold casting is an expendable mold casting process that uses a resin covered sand to form the mold. It is used for small to medium parts that require high dimensional accuracy. The molten metal is poured into an expendable mold, which is typically a thin-walled shell. The pattern, a metal piece in the shape of the desired part, is reused to form multiple shell molds…..Read More

Impro’s unique capabilities are developed to meet the most demanding application requirements in the aerospace, energy and medical industries. We produce high precision and complex machined parts for customers using input material such as bar stock, plates, ingots, billets, and forgings. Whether machining aircraft braking system components, aircraft engine components, or hydraulic parts, which are made of super alloys, stainless steel, aluminum materials;….Read More

Shell Mold Casting

expendable mold casting process

Precision Machining

micro grade tolerances

Impro manufactures and supplies products to the aerospace industry for a wide array of applications. Our products are used in almost all major airframes such as Boeing 737, 777, 787 and Airbus A320, A330, A350, and business jets such as Gulfstream, Embraer, just to name a few.

Impro manufactures numerous parts for the energy markets. From gas turbine fuel nozzle parts to engine emission control products, it is our goal to produce products that help our customers safely break new ground in the evolving energy markets.

Impro manufactures components for medical diagnosis equipment, implants, surgical instruments and patient handling equipment. With Industry-leading total solutions, highly-engineered products, and superior quality control, we have established long-term customer relationships with internationally renowned medical industry leaders. Our medical component production base was accredited with the ISO 13485 certification.

We have been accredited to the AS 9100 certification, and the
NADCAP certification, PED and AD certification.

Worldwide Headquarters

Impro International Limited
Room 1008, Shui On Centre, 6-8
Harbour Road, Wanchai, Hong Kong

Tel: +852 2572 8628
Fax: +852 2572 8638
E-mail: [email protected]

Developer(s)Robert M. (Bob) Keller and others at Harvey Mudd College and elsewhere
Initial release2006 March
Stable release
Operating systemWindows, macOS, Linux

Impro-Visor is an educational tool for creating and playing a lead sheet, with a particular orientation toward representing jazz solos.

Improvisation Advisor[edit]

The philosophy of Impro-Visor is to provide a tool to help musicians construct jazz solos over chord progressions. It includes a database capability for creating, saving, and recalling licks, as well as a lick generation capability based on a user-modifiable grammar. More recent versions of Impro-Visor include auto-generated playback accompaniment in various styles, and a style extraction (from MIDI) capability.Most musical knowledge, including lick generation, database, lead sheets, styles, and other information, is represented as text files, permitting the tool to be customized.

Leadsheet Notation[edit]

Rendering Leadsheet Notation

Impro-Visor saves lead sheets in a textual notation,[1] and lead sheets may be created from that notation as well as by point-and-click. The notation was designed to be friendly to the jazz musician, by resembling directly what appears on the lead sheet staff. For example, the lead sheet fragment to the right, similar to that in article lead sheet, can be created by the following text:


C C7 | F |
c+2 bb2 bb8 a8 f2.

The reading of this text is: Chords C and C7 equally spaced in the first bar, and F in the second bar. A melody of c (the + means an octave above middle C, the 2 means a half-note), bb2, meaning a B-flat half-note, bb8, meaning a B-flat eighth-note, f2., meaning an F dotted half-note. Other meta-data can be supplied, such as for style specification, but is not required.

Tone Categorization[edit]

Using colors for tone categories

Impro-Visor categorizes tones that can be played over any chord into one of four categories.[2] This serves two purposes: (i) as visual feedback to the user, where each category is rendered as a different color, and (ii) as a basis for lick generation. The categories are:

  • Chord tones: tones that are in the chord, and which are thus the most consonant with it (shown as black on the right)
  • Color tones: tones that are not in the chord, but which are also consonant with it (shown as green on the right)
  • Approach tones: tones that are neither of the above, but which approach one of the above chromatically (shown as blue on the right)
  • Other tones: none of the above (shown as red on the right)

The idea is that, aided by visual clues, the musician can learn to appreciate the degree to which a melody will be sonorous over a chord progression prior to hearing it.

Grammatical Lick Generation[edit]

Improper Fractions

Lick generated using grammar to produce notes

Categories of notes discussed above are one of the key ingredients in automating the generation of melodies, which can be used by the musician in constructing solos. The other key ingredient is a context-free grammar having terminal symbols for each of the four categories, along with a few other terminal symbols for convenience. The grammar defines ways in which the melody space can be filled probabilistically by tones of various durations. By associating a probability with each grammar rule, the distribution of generated melodies can be controlled, for example to create melodies that are simple or complex, relatively consonant or dissonant, etc. The user indicates the chord progression, and the grammar drives the melody generation over that progression.[3]

Grammar Learning[edit]

Version 4 added a feature for learning a grammar from a corpus of transcribed solos.[4][5] The learned grammar loosely approximates the playing style of the soloist by creating abstract melodies from the solos, which can be re-instantiated into similar melodies through the grammar. Connections between learned abstract melodic fragments are represented as a Markov chain, which is encoded into the stochastic context-free grammar.


Impro-Visor automatically creates accompaniment, such as piano, bass, and drums, from the chord sequence on a leadsheet (a capability similar to, but currently not as full-featured as that of Band-in-a-Box). The style of accompaniment is derived from a set of pattern specifications using a textual notation similar to that for melodies.[6] For example, a ride cymbal pattern common to swing jazz would be notated as

x4 x8 x8 x4 x8 x8

with x4 signifying a quarter-note hit and x8 an eighth-note hit.The swung note aspect, wherein eighth-notes on the beat get approximately twice the value of the beat, is rendered automatically by a numeric swing parameter, such as .67, which indicates that the beat is divided as .67 + .33 = 1. A similar pattern notation is used for chord comping and bassline patterns. In the latter type of pattern, a note category coding scheme similar to that for the grammatical notation is used to provide probabilistic creation of basslines.

Roadmaps and Analysis of Chord Progressions[edit]

Roadmap produced by Impro-Visor

Impro-Visor analyzes jazz lead sheets to produce a roadmap of the tune. A roadmap is a sequence of bricks that represent harmonic idioms.[7] The nomenclature for this approach is derived from that of Conrad Cork[8] and John Elliott.[9]

See also[edit]

  • Musical improvisation, discussion of improvisation in music
  • Scorewriter, also contains the list of most Notation programs
  • Stochastic context-free grammar, a type of grammar used by Impro-Visor to generate phrases


  1. ^Keller, Robert M. (5 October 2005). 'Impro-Visor Leadsheet Notation'(PDF). Harvey Mudd College. p. 10. Retrieved 5 January 2016.
  2. ^Rober M., Keller; David Morrison; Stephen Jones; Belinda Thom; Aaron Wolin. 'A Computational Framework Enhancing Jazz Creativity'(PDF). Harvey Mudd College. p. 6. Retrieved 5 January 2016.
  3. ^Keller, Rober M.; David R. Morrison (11 July 2007). 'A Grammatical Approach to Automatic Improvisation'(PDF). 4th Sound and Music Computing Conference. p. 8. Retrieved 5 January 2016.
  4. ^Gillick, Jon; Kevin Tang; Robert M. Keller (23 July 2009). 'Learning Jazz Grammars'(PDF). 6th Sound and Music Computing Conference. p. 6. Retrieved 5 January 2016.
  5. ^Gillick, Jon; Kevin Tang; Robert M. Keller (Fall 2010). 'Machine Learning of Jazz Grammars'. Computer Music Journal. 34 (3): 56–66. doi:10.1162/COMJ_a_00006. Retrieved 5 January 2016.
  6. ^Keller, Robert M.; Martin Hunt; Stephen Jones; David Morrison; Aaron Wolin; Steven Gomez (2007). 'Blues for Gary: Design Abstractions for a Jazz Improvisation Assistant'(PDF). Electronic Notes in Theoretical Computer Science (193): 47–60. doi:10.1016/j.entcs.2007.10.007. Retrieved 5 January 2016.
  7. ^Keller, Robert M.; Alexandra Schofield; August Toman-Yih; Zachary Merritt; John Elliott (Winter 2012). 'Automating the Explanation of Jazz Chord Progressions Using Idiomatic Analysis'. Computer Music Journal. 37 (4): 54–69. doi:10.1162/COMJ_a_00201. Retrieved 5 January 2016.
  8. ^Cork, Conrad (2008). The New Guide to Harmony with Lego® Bricks.
  9. ^Elliot, John A. (2009). Insights in Jazz: An Inside View of Jazz Standard Chord Progressions. London: Jazzwise Publications. p. 2. ISBN9780956403117.

Impro Johnstone

External links[edit]


  • Official website
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